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Maccagnani P, Pieruccini M. Impact of Surface States in Graphene/ p-Si Schottky Diodes. Materials (Basel) 2024; 17:1997. [PMID: 38730804 DOI: 10.3390/ma17091997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 04/19/2024] [Accepted: 04/21/2024] [Indexed: 05/13/2024]
Abstract
Graphene-silicon Schottky diodes are intriguing devices that straddle the border between classical models and two-dimensional ones. Many papers have been published in recent years studying their operation based on the classical model developed for metal-silicon Schottky diodes. However, the results obtained for diode parameters vary widely in some cases showing very large deviations with respect to the expected range. This indicates that our understanding of their operation remains incomplete. When modeling these devices, certain aspects strictly connected with the quantum mechanical features of both graphene and the interface with silicon play a crucial role and must be considered. In particular, the dependence of the graphene Fermi level on carrier density, the relation of the latter with the density of surface states in silicon and the coupling between in-plane and out-of-plane dynamics in graphene are key aspects for the interpretation of their behavior. Within the thermionic regime, we estimate the zero-bias Schottky barrier height and the density of silicon surface states in graphene/type-p silicon diodes by adapting a kown model and extracting ideality index values close to unity. The ohmic regime, beyond the flat band potential, is modeled with an empirical law, and the current density appears to be roughly proportional to the electric field at the silicon interface; moreover, the graphene-to-silicon electron tunneling efficiency drops significantly in the transition from the thermionic to ohmic regime. We attribute these facts to (donor) silicon surface states, which tend to be empty in the ohmic regime.
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Affiliation(s)
- Piera Maccagnani
- Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e i Microsistemi, Via P. Gobetti 101, 40129 Bologna, Italy
- Department of Physics and Earth Sciences, University of Ferrara, Via Giuseppe Saragat 1/c, 44122 Ferrara, Italy
| | - Marco Pieruccini
- Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e i Microsistemi, Via P. Gobetti 101, 40129 Bologna, Italy
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2
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Zhang XX, Nagaosa N. Surface spectroscopy and surface-bulk hybridization of Weyl semimetals. Proc Natl Acad Sci U S A 2024; 121:e2313488121. [PMID: 38513104 PMCID: PMC10990132 DOI: 10.1073/pnas.2313488121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 01/30/2024] [Indexed: 03/23/2024] Open
Abstract
Weyl semimetal showing open-arc surface states is a prominent example of topological quantum matter in three dimensions. With the bulk-boundary correspondence present, nontrivial surface-bulk hybridization is inevitable but less understood. Spectroscopies have been often limited to verifying the existence of surface Fermi arcs, whereas its spectral shape related to the hybridization profile in energy-momentum space is not well studied. We present an exactly solvable formalism at the surface for a wide range of prototypical Weyl semimetals. The resonant surface state and the bulk influence coexist as a surface-bulk hybrid and are treated in a unified manner. Directly accessible to angle-resolved photoemission spectroscopy, we analytically reveal universal information about the system obtained from the spectroscopy of resonant topological states. We systematically find inhomogeneous and anisotropic singular responses around the surface-bulk merging borderline crossing Weyl points, highlighting its critical role in the Weyl topology. The response in scanning tunneling spectroscopy is also discussed. The results will provide much-needed insight into the surface-bulk-coupled physical properties and guide in-depth spectroscopic investigation of the nontrivial hybrid in many topological semimetal materials.
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Affiliation(s)
- Xiao-Xiao Zhang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan430074, China
- RIKEN Center for Emergent Matter Science (CEMS), Saitama351-0198, Japan
| | - Naoto Nagaosa
- RIKEN Center for Emergent Matter Science (CEMS), Saitama351-0198, Japan
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Wang X, Zhang C, Liu T, Qin S, Lin Z, Shi C, Zhao D, Zhao Z, Qin X, Li M, Wang Y. Efficient Inverted Perovskite Photovoltaics Through Surface State Manipulation. Small 2024:e2311673. [PMID: 38420901 DOI: 10.1002/smll.202311673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/19/2024] [Indexed: 03/02/2024]
Abstract
Inverted perovskite solar cells (PSCs) are considered as the most promising avenue for the commercialization of PSCs due to their potential inherent stability. However, suboptimal interface contacts between electron transport layer (ETL) (such as C60 ) and the perovskite absorbing layer within inverted PSCs always result in reduced efficiency and poor stability. Herein, a surface state manipulation strategy has been developed by employing a highly electronegative 4-fluorophenethylamine hydrochloride (p-F-PEACl) to effectively address the issue of poor interface contacts in the inverted PSCs. The p-F-PEACl demonstrates a robust interaction with perovskite film through bonding of amino group and Cl- with I- and Pb2+ ions in the perovskite, respectively. As such, the surface defects of perovskite film can be significantly reduced, leading to suppressed non-radiative recombination. Moreover, p-F-PEACl also plays a dual role in enhancing the surface potential and improving energy-level alignment at the interfaces between the perovskite and C60 carrier transport layer, which directly contributes to efficient charge extraction. Finally, the open-circuit voltage (Voc ) of devices increases from 1.104 V to 1.157 V, leading to an overall efficiency improvement from 22.34% to 24.78%. Furthermore, the p-F-PEACl-treated PSCs also display excellent stability.
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Affiliation(s)
- Xingtao Wang
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Chi Zhang
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Tiantian Liu
- School of Chemistry and Chemical Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Shucheng Qin
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Zizhen Lin
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Congbo Shi
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Dongming Zhao
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Zhiguo Zhao
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Xiaojun Qin
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Menglei Li
- Huaneng Clean Energy Research Institute, Beijing, 102209, China
| | - Yong Wang
- State Key Laboratory of Silicon and Advacned Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
- Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310014, China
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Yang T, Yang C. The fluctuated structural/electronic properties of SrTiO 3two-dimensional materials caused by surface effects. J Phys Condens Matter 2024; 36:215001. [PMID: 38364272 DOI: 10.1088/1361-648x/ad2a09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/16/2024] [Indexed: 02/18/2024]
Abstract
Perovskite oxide thin films have many astonishing properties, such as multiferroicity, superconductivity, strong correlation, etc, and are closely related to orientations with different symmetry and structural characteristics. Recently, perovskite oxide films with only one unit cell thickness have been synthesized successfully (Jiet al2019Nature57087-90). Here we investigated the structure and electronic properties of SrTiO3(STO) two-dimensional (2D) materials with (001), (110), and (111) surfaces. We found that due to surface effects caused atomic distortion fluctuations, the lattice constant and thickness of STO 2D materials with the (110) surface fluctuate sharply with the increase of atomic layers. The band gap of STO 2D materials exhibits oscillation as the number of atomic layers increases, due to the different atomic distortion and surface reconstruction with odd and even atomic layers. The STO 2D materials along (001) surfaces with different atomic layers are always semiconductors. As the atomic layers increasing, the electronic structure of STO 2D materials with (110) or (111) surfaces continuously transitioning between semiconductor and metallic phases, and finally totally become metallic phases, which is closely related to the surface reconstruction effect. The differences between STO 2D materials along the (001) and (110) or (111) surfaces are significant and can be explained by mixed Sr-d, Ti-d, and O-p orbitals. Our studies may provide new insights into the surface effects of perovskite oxide 2D materials.
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Affiliation(s)
- Tingkai Yang
- Department of Physics, Jishou University, Hunan 416000, People's Republic of China
| | - Chao Yang
- Department of Physics, Jishou University, Hunan 416000, People's Republic of China
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5
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Wang Z, Lin Z, Wang Y, Shen S, Zhang Q, Wang J, Zhong W. Nontrivial Topological Surface States in Ru 3 Sn 7 toward Wide pH-Range Hydrogen Evolution Reaction. Adv Mater 2023:e2302007. [PMID: 36994807 DOI: 10.1002/adma.202302007] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/21/2023] [Indexed: 06/19/2023]
Abstract
Nontrivial topological surface states (TSSs), which possess extraordinary carrier mobility and are protected by the bulk symmetry, have emerged as an innovative platform to search for efficient electrocatalysts toward hydrogen evolution reaction (HER). Here, a Sn-based nontrivial metal Ru3 Sn7 is prepared using electrical arc melting method. The results indicate that the (001) crystal family of Ru3 Sn7 possesses nontrivial TSSs with linear dispersion relation and large nontrivial energy window. Experimental and theoretical results demonstrate that nontrivial TSSs of Ru3 Sn7 can significantly boost charge transfer kinetics and optimize adsorption of hydrogen intermediates due to bulk symmetry-protected band structures. As expected, nontrivial Ru3 Sn7 exhibits superior HER activity to Ru, Pt/C, and trivial counterparts (e.g., Ru2 Sn3 , IrSn2 , and Rh3 Sn2 ) with higher ratios of noble metals. Furthermore, the wide pH-range activity of topologically nontrivial Ru3 Sn7 implies the robustness of its TSSs against pH variation during the HER. These findings provide a promising approach to the rational design of topologically nontrivial metals as highly efficient electrocatalysts.
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Affiliation(s)
- Zongpeng Wang
- School of Material Science and Engineering, Taizhou University, No. 1139, Shifu Road, Jiaojiang, 318000, China
- School of Material Science and Engineering, Central South University, No. 932, Lushan South Road, Changsha, 410083, China
| | - Zhiping Lin
- School of Material Science and Engineering, Taizhou University, No. 1139, Shifu Road, Jiaojiang, 318000, China
| | - Yinglan Wang
- School of Material Science and Engineering, Taizhou University, No. 1139, Shifu Road, Jiaojiang, 318000, China
| | - Shijie Shen
- School of Material Science and Engineering, Taizhou University, No. 1139, Shifu Road, Jiaojiang, 318000, China
| | - Qinghua Zhang
- Institution of Physics, Chinese Academic of Science, No.8, 3rd Zhongguancun South Street, Beijing, 100190, China
| | - Jiacheng Wang
- School of Material Science and Engineering, Taizhou University, No. 1139, Shifu Road, Jiaojiang, 318000, China
| | - Wenwu Zhong
- School of Material Science and Engineering, Taizhou University, No. 1139, Shifu Road, Jiaojiang, 318000, China
- School of Material Science and Hydrogen Energy, Foshan Institute of Technology, No. 18, Jiangwanyi Road, Foshan, 528000, China
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6
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Deyerling J, Piquero-Zulaica I, Ashoush MA, Seufert K, Kher-Elden MA, Abd El-Fattah ZM, Auwärter W. Formation of an Extended Quantum Dot Array Driven and Autoprotected by an Atom-Thick h-BN Layer. ACS Nano 2023; 17:5448-5458. [PMID: 36884023 DOI: 10.1021/acsnano.2c10366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Engineering quantum phenomena of two-dimensional nearly free electron states has been at the forefront of nanoscience studies ever since the first creation of a quantum corral. Common strategies to fabricate confining nanoarchitectures rely on manipulation or on applying supramolecular chemistry principles. The resulting nanostructures do not protect the engineered electronic states against external influences, hampering the potential for future applications. These restrictions could be overcome by passivating the nanostructures with a chemically inert layer. To this end we report a scalable segregation-based growth approach forming extended quasi-hexagonal nanoporous CuS networks on Cu(111) whose assembly is driven by an autoprotecting h-BN overlayer. We further demonstrate that by this architecture both the Cu(111) surface state and image potential states of the h-BN/CuS heterostructure are confined within the nanopores, effectively forming an extended array of quantum dots. Semiempirical electron-plane-wave-expansion simulations shed light on the scattering potential landscape responsible for the modulation of the electronic properties. The protective properties of the h-BN capping are tested under various conditions, representing an important step toward the realization of robust surface state based electronic devices.
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Affiliation(s)
- Joel Deyerling
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Ignacio Piquero-Zulaica
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Mustafa A Ashoush
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo E-11884, Egypt
| | - Knud Seufert
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Mohammad A Kher-Elden
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo E-11884, Egypt
| | - Zakaria M Abd El-Fattah
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo E-11884, Egypt
| | - Willi Auwärter
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
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7
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Duan C, Zhang L, Wu Z, Wang X, Meng M, Zhang M. Study on the Deterioration Mechanism of Pb on TiO 2 Oxygen Sensor. Micromachines (Basel) 2023; 14:156. [PMID: 36677216 PMCID: PMC9865191 DOI: 10.3390/mi14010156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
Previous studies have shown that the pollutants in exhaust gas can cause performance deterioration in air-fuel oxygen sensors. Although the content of Pb in fuel oil is as low as 5 mg/L, the effect of long-term Pb accumulation on TiO2 oxygen sensors is still unclear. In this paper, the influence mechanism of Pb-containing additives in automobile exhaust gas on the response characteristics of TiO2 oxygen sensors was simulated and studied by depositing Pb-containing pollutants on the surface of a TiO2 sensitive film. It was found that the accumulation of Pb changed the surface gas adsorption state and reduced the activation energy of TiO2, thus affecting the steady-state response voltage and response speed of the TiO2-based oxygen sensor.
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Affiliation(s)
- Chao Duan
- China Aerospace Components Engineering Center, China Academy of Space Technology, Beijing 100081, China
| | - Lejun Zhang
- School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Zhaoxi Wu
- China Aerospace Components Engineering Center, China Academy of Space Technology, Beijing 100081, China
| | - Xu Wang
- China Aerospace Components Engineering Center, China Academy of Space Technology, Beijing 100081, China
| | - Meng Meng
- China Aerospace Components Engineering Center, China Academy of Space Technology, Beijing 100081, China
| | - Maolin Zhang
- School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
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8
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Zhang B, Wang B, Ushakova EV, He B, Xing G, Tang Z, Rogach AL, Qu S. Assignment of Core and Surface States in Multicolor-Emissive Carbon Dots. Small 2022:e2204158. [PMID: 36216592 DOI: 10.1002/smll.202204158] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/16/2022] [Indexed: 06/16/2023]
Abstract
It is important to reveal the luminescence mechanisms of carbon dots (CDs). Herein, CDs with two types of optical centers are synthesized from citric acid in formamide by a solvothermal method, and show high photoluminescence quantum yield reaching 42%. Their green/yellow emission exhibits pronounced vibrational structure and high resistance toward photobleaching, while broad red photoluminescence is sensitive to solvents, temperature, and UV-IR. Under UV-IR, the red emission is gradually bleached due to the photoinduced dehydration of the deprotonated surface of CDs in dimethyl sulfoxide, while this process is hindered in water. From the analysis of steady-state and time-resolved photoluminescence and transient absorption data together with density functional theory calculations, the green/ yellow emission is assigned to conjugated sp2 -domains (core state) similar to organic dye derivatives stacked within disk-shaped CDs; and the broad red emission-to oxygen-containing groups bound to sp2 -domains (surface state), whereas energy transfer from the core to the surface state can happen.
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Affiliation(s)
- Bohan Zhang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau SAR, 999078, P. R. China
| | - Bingzhe Wang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau SAR, 999078, P. R. China
| | - Elena V Ushakova
- Center of Information Optical Technologies, ITMO University, Saint Petersburg, 197101, Russia
| | - Bingchen He
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau SAR, 999078, P. R. China
| | - Guichuan Xing
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau SAR, 999078, P. R. China
| | - Zikang Tang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau SAR, 999078, P. R. China
| | - Andrey L Rogach
- Department of Materials Science and Engineering, and Centre for Functional Photonics (CFP), City University of Hong Kong, Kowloon, Hong Kong SAR, 999077, P. R. China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen, 518057, P. R. China
| | - Songnan Qu
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau SAR, 999078, P. R. China
- Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Macao SAR, 999078, P. R. China
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9
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Meng F, Lin Z, Li W, Yan P, Zheng Y, Li X, Jiang J, Jia B, Huang X. Observation of Emergent Dirac Physics at the Surfaces of Acoustic Higher-Order Topological Insulators. Adv Sci (Weinh) 2022; 9:2201568. [PMID: 36035068 PMCID: PMC9404400 DOI: 10.1002/advs.202201568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/29/2022] [Indexed: 05/19/2023]
Abstract
Using 3D sonic crystals as acoustic higher-order topological insulators (HOTIs), 2D surface states described by spin-1 Dirac equations at the interfaces between the two sonic crystals with distinct topology but the same crystalline symmetry are discovered. It is found that the Dirac mass can be tuned by the geometry of the two sonic crystals. The sign reversal of the Dirac mass reveals a surface topological transition where the surface states exhibit zero refractive index behavior. When the surface states are gapped, 1D hinge states emerge due to the topology of the gapped surface states. The zero refractive index behavior and the emergent topological hinge states are confirmed experimentally. This study reveals a multidimensional Wannier orbital control that leads to extraordinary properties of surface states and unveils an interesting topological mechanism for the control of surface waves.
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Affiliation(s)
- Fei Meng
- Hubei Key Laboratory of Roadway Bridge and Structure EngineeringWuhan University of TechnologyWuhanHubei430070P. R. China
- Centre of Translational AtomaterialsFaculty of ScienceEngineering and TechnologySwinburne University of TechnologyHawthornVIC3122Australia
| | - Zhi‐Kang Lin
- School of Physical Science and Technologyand Collaborative Innovation Center of Suzhou Nano Science and TechnologySoochow UniversitySuzhou215006P. R. China
| | - Weibai Li
- Centre of Translational AtomaterialsFaculty of ScienceEngineering and TechnologySwinburne University of TechnologyHawthornVIC3122Australia
| | - Peiguang Yan
- Key Laboratory of Optoelectronic Devices and SystemsCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen518060P. R. China
| | - Yun Zheng
- State Key Laboratory of Geomechanics and Geotechnical EngineeringInstitute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071P. R. China
| | - Xinping Li
- Hubei Key Laboratory of Roadway Bridge and Structure EngineeringWuhan University of TechnologyWuhanHubei430070P. R. China
| | - Jian‐Hua Jiang
- School of Physical Science and Technologyand Collaborative Innovation Center of Suzhou Nano Science and TechnologySoochow UniversitySuzhou215006P. R. China
| | - Baohua Jia
- Centre of Translational AtomaterialsFaculty of ScienceEngineering and TechnologySwinburne University of TechnologyHawthornVIC3122Australia
| | - Xiaodong Huang
- Centre of Translational AtomaterialsFaculty of ScienceEngineering and TechnologySwinburne University of TechnologyHawthornVIC3122Australia
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Yao Q, Liang T, Wu H, Xi X, Fan J. Cooccurrence of pH-sensitive shifting blue and immobile green triple surface-state fluorescence in ultrasmall super body-centered cubic carbon quantum dots. Nanotechnology 2022; 33:385704. [PMID: 35705025 DOI: 10.1088/1361-6528/ac78f2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
Carbon quantum dots are widely used in various fields owing to excellent optical properties and outstanding biocompatibility. We synthesize rare super body-centered cubic (C8) structured carbon quantum dots by using cheap source materials and simple preparation method. They exhibit one shifting blue emission band and two close immobile green bands. They have large Stokes shifts ranging from 0.68 to 1.01 eV and large quantum yields as high as 60%. The three types of emissions are competitive and their intensities vary sensitively and differently with pH. Moreover, their emission intensity versus excitation power curves followI(P)∝Pkwithkvalues significantly smaller than unity. The blue emission follows the stretched exponential decay law with an intermediate lifetime of ∼3.9 ns and a lifetime-dispersion factor of ∼0.85 whereas the two green emissions exhibit faster and slower decays with respective lifetimes of around 2.0 and 13.0 ns. The results reveal that the blue emission originates from an ensemble of emission sites exhibiting quantum confinement-like effect and two green emissions stem from pH-sensitive surface functional groups-associated fluorophores.
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Affiliation(s)
- Qianqin Yao
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Tianyuan Liang
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Huaxin Wu
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Xiaonan Xi
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
| | - Jiyang Fan
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
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11
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Abbas MA, Bang JH. Surface State-Assisted Delayed Photocurrent Response of Au Nanocluster/TiO 2 Photoelectrodes. ACS Appl Mater Interfaces 2022; 14:25409-25416. [PMID: 35608651 DOI: 10.1021/acsami.2c03883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Gold nanoclusters (NCs) can be used as sensitizers to extend the absorption capabilities of TiO2 as photoelectrodes. However, the adsorption of NCs also creates additional surface states on the TiO2 surface, which gives rise to intricacies in the understanding of various interfacial phenomena occurring in NC-sensitized TiO2. One of the complexities that have recently been discovered is the size-dependent hole-transfer mechanism. In this work, we reveal another anomalous behavior in the hole-transfer process that the hole scavenging ability of the electrolyte also plays a role in determining the hole-transfer mechanism in the NC-TiO2 system, which is unprecedented in other photoelectrode systems. In the presence of an efficient hole scavenger (Na2SO3), the hole transfer in Au18-TiO2 occurs directly through the highest occupied molecular orbital (HOMO) of Au18 NCs. However, in the presence of a less efficient hole scavenger (ethylenediaminetetraacetic acid), hole transfer in Au18-TiO2 does not occur through the HOMO and shifts to surface state-assisted hole transfer. Due to surface state charging, this surface state-assisted hole-transfer mechanism results in delayed photocurrent response in Au18-TiO2. Evidence for this exotic hole-transfer mechanism shift is provided by photoelectrochemical electrochemical impedance spectroscopy, and its implications are discussed.
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Affiliation(s)
- Muhammad A Abbas
- Nanosensor Research Institute, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Jin Ho Bang
- Nanosensor Research Institute, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
- Department of Chemical and Molecular Engineering, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
- Department of Applied Chemistry, Center for Bionano Intelligence Education and Research, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
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12
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Zhang XX, Nagaosa N. Anisotropic Three-Dimensional Quantum Hall Effect and Magnetotransport in Mesoscopic Weyl Semimetals. Nano Lett 2022; 22:3033-3039. [PMID: 35332773 PMCID: PMC9011404 DOI: 10.1021/acs.nanolett.2c00296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/08/2022] [Indexed: 06/14/2023]
Abstract
Weyl semimetals are emerging to become a new class of quantum-material platform for various novel phenomena. Especially, the Weyl orbit made from surface Fermi arcs and bulk relativistic states is expected to play a key role in magnetotransport, leading even to a three-dimensional quantum Hall effect (QHE). It is experimentally and theoretically important although yet unclear whether it bears essentially the same phenomenon as the conventional two-dimensional QHE. We discover an unconventional fully three-dimensional anisotropy in the quantum transport under a magnetic field. Strong suppression and even disappearance of the QHE occur when the Hall-bar current is rotated away from being transverse to parallel with respect to the Weyl point alignment, which is attributed to a peculiar absence of conventional bulk-boundary correspondence. Besides, transport along the magnetic field can exhibit a remarkable reversal from negative to positive magnetoresistance. These results establish the uniqueness of this QHE system as a novel three-dimensional quantum matter.
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Affiliation(s)
- Xiao-Xiao Zhang
- RIKEN
Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Naoto Nagaosa
- RIKEN
Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Department
of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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13
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Ishida H. Spin-dependent band-gap formation for the L-gap surface state on the(22×3)reconstructed Au(111) surface. J Phys Condens Matter 2022; 34:195002. [PMID: 35168209 DOI: 10.1088/1361-648x/ac553a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
We elucidate how the free-electron-like energy dispersion of theL-gap surface state on a Au(111)-(1 × 1) surface is modified by the experimentally observed uniaxial reconstruction of the topmost atomic layer. For this purpose, we perform a first-principles embedded Green's function calculation for the(22×3)reconstructed semi-infinite Au(111) surface. The obtained band structure unfolded into the surface Brillouin zone of the (1 × 1) surface can be understood in terms of two spin-split parabolic bands centered at theΓ¯point, their umklapp-induced replicas centered at reciprocal lattice vectors of the superlattice (SL) with much weaker intensities, and mini band gaps at the crossing of two of them. More importantly, it is revealed that the band-gap size depends not only on the amplitude of the SL potential but also on mutual spin orientations of two crossing bands. Furthermore, we demonstrate that the band-gap size and the charge density distribution of the surface states are closely correlated with spatial profile of the SL potential.
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Affiliation(s)
- H Ishida
- College of Humanities and Sciences, Nihon University, Sakura-Josui, Tokyo 156-8550, Japan
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14
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Mao Z, Li H, Gan N, Suo Z, Zhang H, Zhao Q. Contribution of nicotinamide as an intracyclic N dopant to the structure and properties of carbon dots synthesized using three α-hydroxy acids as C sources. Nanotechnology 2022; 33:215705. [PMID: 35168216 DOI: 10.1088/1361-6528/ac553e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Fixed carbon source and different dopants are mainly used to study the effect of heteroatoms on the structure and properties of carbon dots (CDs). As reactants, some dopants with conjugated structure and high nitrogen content may have important contributions to the structure and properties of doped CDs in addition to providing heteroatoms. Herein, to study the effect of fixed dopant on the structure and properties of CDs, three different CDs were synthesized using nicotinamide (NAA) and three commonα-hydroxy acids (4-5 carbon atoms), and the optimal conditions were determined by orthogonal experimentation. Transmission electron microscopic micrographs showed that the average size of CDs based on nicotinamide are relatively large, up to 19.40 nm. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy demonstrated that these CDs have graphite nitrogen and several functional group structures. Ultraviolet-visible absorption spectra, fluorescence emission spectra, and fluorescence lifetime illustrated that these CDs have similar emission centers (460-470 nm) and fluorescence processes. The influence of carbon source on the surface structure of CDs was determined by systematically analyzing the response of these CDs in different pH ranges. DFT calculations revealed the distribution characteristics of the electrons in the excited state at the HOMO and LUMO energy levels of CDs. All the above characterizations and calculations proved that NAA is a desirable dopant with an important contribution to the structure and properties of CDs.
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Affiliation(s)
- Zhen Mao
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Hui Li
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Na Gan
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Zili Suo
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Huan Zhang
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Qiang Zhao
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
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15
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Čilliková M, Mičietová A, Čep R, Jacková M, Minárik P, Neslušan M, Kouřil K. Analysis of Surface State after Turning of High Tempered Bearing Steel. Materials (Basel) 2022; 15:1718. [PMID: 35268946 DOI: 10.3390/ma15051718] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/15/2022] [Accepted: 02/22/2022] [Indexed: 02/04/2023]
Abstract
This paper investigates surface state after turning of the high tempered bearing steel 100Cr6 with a hardness of 40 HRC. White layer (WL) thickness and its microhardness, as well as surface roughness, are investigated as a function of tool flank wear VB as well as cutting speed vc. The mechanical and thermal load of the machined surface were analysed in order to provide a deeper insight into their superimposing contribution. Cutting energy expressed in terms of cutting force was analyses as that consumed for chip formation Fγ and consumed in the flank wear land Fα. It was found that the mechanical energy expressed in terms of the shear components of the Fα grows with VB, converts to the heat and strongly affects the thickness of the re-hardened layer. Furthermore, the superimposing contribution of the heat generation and its duration in the VB region should also be taken into account. It was also found that the influence of VB predominates over the variable cutting speed.
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16
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Qi J, Liu H, Xu H, Hu L, Wang C, Zhang Y, Feng M, Lü W. Surface Atomic Decoration of a Manganite to a Modulable Oxygen Evolution Reaction. ACS Appl Mater Interfaces 2021; 13:61267-61274. [PMID: 34914875 DOI: 10.1021/acsami.1c19938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Aiming at the fundamental understanding of oxygen evolution reaction (OER) in epitaxial perovskite transition metal oxide (TMO) thin films, we evaluate the surface decoration conditions, including lattice orientation and surface morphology, of La2/3Sr1/3MnO3 (LSMO) related to its modulable OER performance. The LSMOs with orientations of (001), (110), and, (111) exhibit different OER activities owing to the discrepant surface density of Mn. Furthermore, tuning of the surface atomic terrace width of LSMO shows a more efficient path to modulate the OER performance by introducing a high-valence Mn state owing to the surface dangling bonds of LSMO. As the electrochemical process is dominated by the interface of the TMO surface and electrolyte, our investigation can approach the fundamental understanding of a perovskite-type TMO surface state and its OER performance while highlighting the role of the nonbulk electron state in a promising TMO electrocatalyst in abundant electrochemical processes.
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Affiliation(s)
- Ji Qi
- Condensed Matter Science and Technology Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150080, China
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Huan Liu
- Condensed Matter Science and Technology Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150080, China
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Hang Xu
- Condensed Matter Science and Technology Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150080, China
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Linglong Hu
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Chen Wang
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Yuan Zhang
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Ming Feng
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
| | - Weiming Lü
- Condensed Matter Science and Technology Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150080, China
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China
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17
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Zhang L, Fang F, Cheng L, Lin H, Wang K. Obvious Surface States Connecting to the Projected Triple Points in NaCl's Phonon Dispersion. Front Chem 2021; 9:789522. [PMID: 34869236 PMCID: PMC8634720 DOI: 10.3389/fchem.2021.789522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 10/18/2021] [Indexed: 12/03/2022] Open
Abstract
With the development of computer technology and theoretical chemistry, the speed and accuracy of first-principles calculations have significantly improved. Using first-principles calculations to predict new topological materials is a hot research topic in theoretical and computational chemistry. In this work, we focus on a well-known material, sodium chloride (NaCl), and propose that the triple point (TP), quadratic contact triple point (QCTP), linear and quadratic nodal lines can be found in the phonon dispersion of NaCl with Fm3¯ m type structure. More importantly, we propose that the clear surface states connected to the projected TP and QCTP are visible on the (001) surface. It is hoped that further experimental investigation and verification for these properties as mentioned above.
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Affiliation(s)
- Li Zhang
- 'College of Mechanics, Changchun Institute of Technology, Changchun, China
| | - Fang Fang
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China
| | - Lixin Cheng
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China
| | - Huiming Lin
- School of Chemistry, Harbin Normal University, Harbin, China
| | - Kai Wang
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China
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18
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Han L, Lin J, Liu J, Fahrenkrug E, Guan Y, Sun K, Wang Y, Liu K, Wang Z, Wang Z, Qu S, Jin P. Spatioselective Growth on Homogenous Semiconductor Substrates by Surface State Modulation. Nano Lett 2021; 21:5931-5937. [PMID: 34176272 DOI: 10.1021/acs.nanolett.1c00689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanofabrication schemes usually suffer challenges in direct growth on complex nanostructured substrates. We provide a new technology that allows for the convenient, selective growth of complex nanostructures directly on three-dimensional (3D) homogeneous semiconductor substrates. The nature of the selectivity is derived from surface states modulated electrochemical deposition. Metals, metal oxides, and compound semiconductor structures can be prepared with high fidelity over a wide scale range from tens of nanometers to hundreds of microns. The utility of the process for photoelectrochemical applications is demonstrated by selectively decorating the sidewalls and tips of silicon microwires with cuprous oxide and cobalt oxides catalysts, respectively. Our findings indicate a new selective fabrication concept applied for homogeneous 3D semiconductor substrates, which is of high promise in community of photoelectronics, photoelectrochemistry, photonics, microelectronics, etc.
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Affiliation(s)
| | | | - Jun Liu
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Eli Fahrenkrug
- Department of Chemistry, Colorado College, 4 East Cache la Poudre, Colorado Springs, Colorado 80903, United States
| | | | | | | | - Kong Liu
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Zhijie Wang
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Zhanguo Wang
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Shengchun Qu
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
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19
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Lan Y, Kang S, Cui D, Hu Z. A High-Efficiency Hematite Photoanode with Enhanced Bonding Energy Around Fe Atoms. Chemistry 2021; 27:4089-4097. [PMID: 33242224 DOI: 10.1002/chem.202004569] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/12/2020] [Indexed: 01/20/2023]
Abstract
Hematite nanoarrays are important photoanode materials. However, they suffer from serious problems of charge transfer and surface states; in particular, the surface states hinder the increase in photocurrent. A previous strategy to suppress the surface state is the deposition of an Fe-free metal oxide overlayer. Herein, from the viewpoint of atomic bonding energy, it is found that the strength of bonding around Fe atoms in the hematite is the key to suppressing the surface states. By treating the surface of hematite with Se and NaBH4 , the Fe2 O3 transforms to a double-layer nanostructure. In the outer layer, the Fe-O bonding is reinforced and the Fe-Se bonding is even stronger. Therefore, the surface states are inhibited and the increase in the photocurrent density becomes much faster. Besides, the treatment constructs a nanoscale p-n junction to promote the charge transfer. Improvements are achieved in onset potential (0.25 V shift) and in photocurrent density (5.8 times). This work pinpoints the key to suppressing the surface states and preparing a high-efficiency hematite nanoarray, and deepens our understanding of hematite photoanodes.
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Affiliation(s)
- Yangchun Lan
- School of Microelectronics, Southern University of Science, and Technology, Shenzhen, 518055, P. R. China
| | - Shuai Kang
- Micro-nano Manufacturing and System Integration Center, Chongqing Institute of Green and Intelligent Technology (CIGIT), Chinese Academy of Sciences, Chongqing, 400714, P. R. China
| | - Dehu Cui
- School of Microelectronics, Southern University of Science, and Technology, Shenzhen, 518055, P. R. China
| | - Zhuofeng Hu
- School of Environmental Science and Engineering, Guangdong, Provincial Key Laboratory of, Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, P. R. China
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20
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Kim TY, Kim BS, Oh JG, Park SC, Jang J, Hamann TW, Kang YS, Bang JH, Giménez S, Kang YS. Interfacial Engineering at Quantum Dot-Sensitized TiO 2 Photoelectrodes for Ultrahigh Photocurrent Generation. ACS Appl Mater Interfaces 2021; 13:6208-6218. [PMID: 33523646 PMCID: PMC8576758 DOI: 10.1021/acsami.0c19352] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Metal oxide semiconductor/chalcogenide quantum dot (QD) heterostructured photoanodes show photocurrent densities >30 mA/cm2 with ZnO, approaching the theoretical limits in photovoltaic (PV) cells. However, comparative performance has not been achieved with TiO2. Here, we applied a TiO2(B) surface passivation layer (SPL) on TiO2/QD (PbS and CdS) and achieved a photocurrent density of 34.59 mA/cm2 under AM 1.5G illumination for PV cells, the highest recorded to date. The SPL improves electron conductivity by increasing the density of surface states, facilitating multiple trapping/detrapping transport, and increasing the coordination number of TiO2 nanoparticles. This, along with impeded electron recombination, led to enhanced collection efficiency, which is a major factor for performance. Furthermore, SPL-treated TiO2/QD photoanodes were successfully exploited in photoelectrochemical water splitting cells, showing an excellent photocurrent density of 14.43 mA/cm2 at 0.82 V versus the Reversible Hydrogen Electrode (RHE). These results suggest a new promising strategy for the development of high-performance photoelectrochemical devices.
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Affiliation(s)
- Tea-Yon Kim
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322, United States
| | - Byung Su Kim
- Department
of Energy Engineering and Center for Next Generation Dye-Sensitized
Solar Cells, Hanyang University, Seoul 04763, Korea
| | - Jong Gyu Oh
- Department
of Energy Engineering, Hanyang University, Seoul 04763, Korea
| | - Seul Chan Park
- Department
of Energy Engineering and Center for Next Generation Dye-Sensitized
Solar Cells, Hanyang University, Seoul 04763, Korea
| | - Jaeyoung Jang
- Department
of Energy Engineering, Hanyang University, Seoul 04763, Korea
| | - Thomas W. Hamann
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322, United States
| | - Young Soo Kang
- Korea
Center for Artificial Photosynthesis and Department of Chemistry, Sogang University, Seoul 04107, Korea
| | - Jin Ho Bang
- Department
of Chemical and Molecular Engineering and Department of Applied Chemistry,
Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 15588, Gyeonggi-do, Korea
| | - Sixto Giménez
- Institute
of Advanced Materials (INAM), Universitat
Jaume I, Castelló 12006, Spain
| | - Yong Soo Kang
- Department
of Energy Engineering and Center for Next Generation Dye-Sensitized
Solar Cells, Hanyang University, Seoul 04763, Korea
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21
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Kułakowska A, Bohdal Ł. Researches and Simulation of Elastic Recovery Phenomena during Roller Burnishing Process of Macro-Asperities of Surface. Materials (Basel) 2020; 13:E5276. [PMID: 33233465 DOI: 10.3390/ma13225276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/09/2020] [Accepted: 11/18/2020] [Indexed: 11/16/2022]
Abstract
The paper presents preliminary studies of a new innovative surface treatment method-the process of roller burnishing of macro-irregularities of the surface. As part of the work, the possibility of plastic shaping of the surface macrostructure with indentations (plateau structure), which will show anti-wear properties through appropriate surface shaping and the compressive stress state in the product's top layer, was investigated. The essence of the paper is the analysis of one of the aspects of the application of this processing method, i.e., the influence of the elastic recovery of the product on its technological quality measured by dimensional deviation. The main objective of the work is to develop adequate methods and mathematical models to enable the design of the macro-asperities of the surface burnishing process to maintain the dimensional tolerance of the shaped parts. The results of dependencies of elastic recovery of the asperities and the deviation of height, Δht, for sample depths of burnishing were presented. The model tests of the elastic recovery of the model material using the visioplasticity method show that with the increase of the value of the vertical surface asperities, the value of the elastic recovery of the material decreases. The increase of the deviation of the asperities' height causes a decrease in the value of elastic recovery. With the increase of the value of the vertical angle of the surface roughness, the value of the elastic recovery of the material is smaller.
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22
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Chong YX, Liu X, Sharma R, Kostin A, Gu G, Fujita K, Davis JCS, Sprau PO. Severe Dirac Mass Gap Suppression in Sb 2Te 3-Based Quantum Anomalous Hall Materials. Nano Lett 2020; 20:8001-8007. [PMID: 32985892 DOI: 10.1021/acs.nanolett.0c02873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The quantum anomalous Hall (QAH) effect appears in ferromagnetic topological insulators (FMTIs) when a Dirac mass gap opens in the spectrum of the topological surface states (SSs). Unaccountably, although the mean mass gap can exceed 28 meV (or ∼320 K), the QAH effect is frequently only detectable at temperatures below 1 K. Using atomic-resolution Landau level spectroscopic imaging, we compare the electronic structure of the archetypal FMTI Cr0.08(Bi0.1Sb0.9)1.92Te3 to that of its nonmagnetic parent (Bi0.1Sb0.9)2Te3, to explore the cause. In (Bi0.1Sb0.9)2Te3, we find spatially random variations of the Dirac energy. Statistically equivalent Dirac energy variations are detected in Cr0.08(Bi0.1Sb0.9)1.92Te3 with concurrent but uncorrelated Dirac mass gap disorder. These two classes of SS electronic disorder conspire to drastically suppress the minimum mass gap to below 100 μeV for nanoscale regions separated by <1 μm. This fundamentally limits the fully quantized anomalous Hall effect in Sb2Te3-based FMTI materials to very low temperatures.
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Affiliation(s)
- Yi Xue Chong
- LASSP, Department of Physics, Cornell University, Ithaca, New York 14853, United States
- CMPMS Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Xiaolong Liu
- LASSP, Department of Physics, Cornell University, Ithaca, New York 14853, United States
- Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, United States
| | - Rahul Sharma
- LASSP, Department of Physics, Cornell University, Ithaca, New York 14853, United States
- CMPMS Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Andrey Kostin
- LASSP, Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Genda Gu
- CMPMS Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - K Fujita
- CMPMS Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - J C Séamus Davis
- LASSP, Department of Physics, Cornell University, Ithaca, New York 14853, United States
- Department of Physics, University College Cork, Cork T12R5C, Ireland
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, U.K
| | - Peter O Sprau
- LASSP, Department of Physics, Cornell University, Ithaca, New York 14853, United States
- Advanced Development Center, ASML, Wilton, Connecticut 06897, United States
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23
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Feng J, Lotnyk A, Bryja H, Wang X, Xu M, Lin Q, Cheng X, Xu M, Tong H, Miao X. "Stickier"-Surface Sb 2Te 3 Templates Enable Fast Memory Switching of Phase Change Material GeSb 2Te 4 with Growth-Dominated Crystallization. ACS Appl Mater Interfaces 2020; 12:33397-33407. [PMID: 32597166 DOI: 10.1021/acsami.0c07973] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ge-Sb-Te (GST)-based phase-change memory (PCM) excels in the switching performance but remains insufficient of the operating speed to replace cache memory (the fastest memory in a computer). In this work, a novel approach using Sb2Te3 templates is proposed to boost the crystallization speed of GST by five times faster. This is because such a GST/Sb2Te3 heterostructure changes the crystallizing mode of GST from the nucleation-dominated to the faster growth-dominated one, as confirmed by high-resolution transmission electron microscopy, which captures the interface-induced epitaxial growth of GST on Sb2Te3 templates in devices. Ab initio molecular dynamic simulations reveal that Sb2Te3 templates can render GST sublayers faster crystallization speed because Sb2Te3's "sticky" surface contains lots of unpaired electrons that may attract Ge atoms with less antibonding interactions. Our work not only proposes a template-assisted PCM with fast speed but also uncovers the hidden mechanism of Sb2Te3's sticky surface, which can be used for future material selection.
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Affiliation(s)
- Jinlong Feng
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, Leipzig 04318, Germany
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Andriy Lotnyk
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, Leipzig 04318, Germany
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies, Ningbo University, Ningbo 315211, China
| | - Hagen Bryja
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, Leipzig 04318, Germany
| | - Xiaojie Wang
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Meng Xu
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qi Lin
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiaomin Cheng
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ming Xu
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Hao Tong
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiangshui Miao
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
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24
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Musiał J, Horiashchenko S, Polasik R, Musiał J, Kałaczyński T, Matuszewski M, Śrutek M. Abrasion Wear Resistance of Polymer Constructional Materials for Rapid Prototyping and Tool-Making Industry. Polymers (Basel) 2020; 12:E873. [PMID: 32290260 DOI: 10.3390/polym12040873] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 11/26/2022] Open
Abstract
The original test results of abrasive wear resistance of different type of construction polymer materials were presented and discussed in this article. Tests were made on an adapted test stand (surface grinder for form and finish grinding). Test samples were made of different types of polymer board materials including RenShape®, Cibatool® and phenolic cotton laminated plastic laminate (TCF). An original methodology based on a grinding experimental set-up of abrasion wear resistance of polymer construction materials was presented. Equations describing relations between material type and wear resistance were presented and discussed. Micro and macro structures were investigated and used in wear resistance prediction.
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25
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Yu J, Zhang C, Pang G, Sun XW, Chen R. Effect of Lateral Size and Surface Passivation on the Near-Band-Edge Excitonic Emission from Quasi-Two-Dimensional CdSe Nanoplatelets. ACS Appl Mater Interfaces 2019; 11:41821-41827. [PMID: 31613084 DOI: 10.1021/acsami.9b16044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
As a new type of quasi-two-dimensional nanomaterial, CdSe nanoplatelets (NPLs) possess excellent properties such as narrow emission peak, large absorption cross section, and a low threshold of amplified spontaneous emission. However, the origin of emission especially at low temperatures has not been studied clearly up till now. Here, we study the temperature-dependent photoluminescence of CdSe NPLs which show two emission peaks at low temperatures. It is interesting to note that the intensity of the low-energy peak shows a correlation with laser irradiation time. Moreover, the low-temperature PL spectra of four CdSe NPLs with different lateral sizes demonstrate the relationship of low-energy peaks with the surface. It has been confirmed that CdSe NPLs with larger surface areas to volume ratio have stronger low-energy emissions, which is ascribed to the surface-state-related emission. Finally, surface passivation of CdSe NPLs attenuates the intensity of the low-energy peak, which further verifies our model. Our results demonstrate the critical significance of surface in CdSe NPLs for their optical properties, which is crucial for the application of optoelectronic devices.
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Affiliation(s)
- Jiahao Yu
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
- Harbin Institute of Technology , Harbin 150001 , P. R. China
| | - Chaojian Zhang
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
| | - Guotao Pang
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
| | - Xiao Wei Sun
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
| | - Rui Chen
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
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26
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Zhao D, Liu X, Zhang Z, Zhang R, Liao L, Xiao X, Cheng H. Synthesis of Multicolor Carbon Dots Based on Solvent Control and Its Application in the Detection of Crystal Violet. Nanomaterials (Basel) 2019; 9:nano9111556. [PMID: 31683937 PMCID: PMC6915586 DOI: 10.3390/nano9111556] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023]
Abstract
The adjustment of the emitting wavelength of carbon dots (CDs) is usually realized by changing the raw materials, reaction temperature, or time. This paper reported the effective synthesis of multicolor photoluminescent CDs only by changing the solvent in a one-step solvothermal method, with 1,2,4,5-tetraaminobenzene as both the novel carbon source and nitrogen source. The emission wavelengths of the as-prepared CDs ranged from 527 to 605 nm, with quantum yields (QYs) reaching 10.0% to 47.6%, and it was successfully employed as fluorescence ink. The prepared red-emitting CDs (R-CDs, λem = 605 nm) and yellow-emitting CDs (Y-CDs, λem = 543 nm) were compared through multiple characterization methods, and their luminescence mechanism was studied. It was discovered that the large particle size, the existence of graphite Ns, and oxygen-containing functional groups are beneficial to the formation of long wavelength-emitting CDs. Y-CDs responded to crystal violet, and its fluorescence could be quenched. This phenomenon was thus employed to develop a detection method for crystal violet with a linear range from 0.1 to 11 µM and a detection limit of 20 nM.
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Affiliation(s)
- Dan Zhao
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Xuemei Liu
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Zhixia Zhang
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Rui Zhang
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Liangxiu Liao
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Xincai Xiao
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
| | - Han Cheng
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan 430074, China.
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Jiang K, Feng X, Gao X, Wang Y, Cai C, Li Z, Lin H. Preparation of Multicolor Photoluminescent Carbon Dots by Tuning Surface States. Nanomaterials (Basel) 2019; 9:E529. [PMID: 30987120 PMCID: PMC6523770 DOI: 10.3390/nano9040529] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/21/2019] [Accepted: 03/25/2019] [Indexed: 12/12/2022]
Abstract
The achievements of multicolor photoluminescent (PL)-emissive carbon dots (CDs), particularly red to near infrared (NIR), are critical for their applications in optoelectronic devices and bioimaging, but it still faces great challenges to date. In this study, PL emission red-shifts were observed when tartaric acid (TA) was added into m-phenylenediamine (mPD) or o-phenylenediamine (oPD) solutions as carbon sources to prepare CDs, i.e., from blue to green for mPD and from yellow-green to red for oPD. Morphology and structure analyses revealed that the increased surface oxidation and carboxylation were responsible for the red-shifts of emission, indicating that TA played a key role in tuning the surface state of CDs. These factors could be employed as effective strategies to adjust PL emissions of CDs. Consequently, multicolor PL CDs (i.e., blue-, green-, yellow-green- and red-emissive CDs) can be facilely prepared using mPD and oPD in the absence and presence of TA. Particularly, the obtained red-emissive CDs showed a high PL quantum yield up to 22.0% and an emission covering red to NIR regions, demonstrating great potentials in optoelectronic devices and bioimaging. Moreover, multicolor phosphors were further prepared by mixing corresponding CDs with polyvinylpyrrolidone (PVP), among which the blue, green, and red ones could serve as three primary color phosphors for fabricating multicolor and white light-emitting diodes (LEDs). The white LED was measured to show a Commission Internationale de L'Eclairage (CIE) 1931 chromaticity coordinate of (0.34, 0.32), a high color rendering index (CRI) of 89, and a correlated color temperature (CCT) of 5850 K, representing one of the best performances of white LEDs based on CDs.
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Affiliation(s)
- Kai Jiang
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Department of Applied Physics, Chongqing University, Chongqing 400044, China.
- Key Laboratory of Graphene Technologies and Applications of Zhejiang Province & Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, China.
| | - Xiangyu Feng
- Key Laboratory of Graphene Technologies and Applications of Zhejiang Province & Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, China.
| | - Xiaolu Gao
- Key Laboratory of Graphene Technologies and Applications of Zhejiang Province & Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, China.
| | - Yuhui Wang
- Key Laboratory of Graphene Technologies and Applications of Zhejiang Province & Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, China.
| | - Congzhong Cai
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, Department of Applied Physics, Chongqing University, Chongqing 400044, China.
| | - Zhongjun Li
- College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China.
| | - Hengwei Lin
- Key Laboratory of Graphene Technologies and Applications of Zhejiang Province & Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, China.
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28
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Yan JM, Xu ZX, Chen TW, Xu M, Zhang C, Zhao XW, Liu F, Guo L, Yan SY, Gao GY, Wang FF, Zhang JX, Dong SN, Li XG, Luo HS, Zhao W, Zheng RK. Nonvolatile and Reversible Ferroelectric Control of Electronic Properties of Bi 2Te 3 Topological Insulator Thin Films Grown on Pb(Mg 1/3Nb 2/3)O 3-PbTiO 3 Single Crystals. ACS Appl Mater Interfaces 2019; 11:9548-9556. [PMID: 30724082 DOI: 10.1021/acsami.8b20406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Single-phase (00 l)-oriented Bi2Te3 topological insulator thin films have been deposited on (111)-oriented ferroelectric 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) single-crystal substrates. Taking advantage of the nonvolatile polarization charges induced by the polarization direction switching of PMN-PT substrates at room temperature, the carrier density, Fermi level, magnetoconductance, conductance channel, phase coherence length, and quantum corrections to the conductance can be in situ modulated in a reversible and nonvolatile manner. Specifically, upon the polarization switching from the positively poled Pr+ state (i.e., polarization direction points to the film) to the negatively poled Pr- (i.e., polarization direction points to the bottom electrode) state, both the electron carrier density and the Fermi wave vector decrease significantly, reflecting a shift of the Fermi level toward the Dirac point. The polarization switching from Pr+ to Pr- also results in significant increase of the conductance channel α from -0.15 to -0.3 and a decrease of the phase coherence length from 200 to 80 nm at T = 2 K as well as a reduction of the electron-electron interaction. All these results demonstrate that electric-voltage control of physical properties using PMN-PT as both substrates and gating materials provides a simple and a straightforward approach to realize reversible and nonvolatile tuning of electronic properties of topological thin films and may be further extended to study carrier density-related quantum transport properties of other quantum matter.
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Affiliation(s)
- Jian-Min Yan
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Zhi-Xue Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Ting-Wei Chen
- School of Materials Science and Engineering , Nanchang University, and Jiangxi Engineering Laboratory for Advanced Functional Thin Films , Nanchang 330031 , China
| | - Meng Xu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Chao Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Xu-Wen Zhao
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Fei Liu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Lei Guo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Shu-Ying Yan
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Guan-Yin Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Fei-Fei Wang
- Key Laboratory of Optoelectronic Material and Device, Department of Physics , Shanghai Normal University , Shanghai 200234 , China
| | - Jin-Xing Zhang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Si-Ning Dong
- Department of Physics , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Xiao-Guang Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures , University of Science and Technology of China , Hefei 230026 , China
| | - Hao-Su Luo
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
| | - Weiyao Zhao
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- ISEM, Innovation Campus , University of Wollongong , Wollongong , New South Wales 2500 , Australia
| | - Ren-Kui Zheng
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China
- School of Materials Science and Engineering , Nanchang University, and Jiangxi Engineering Laboratory for Advanced Functional Thin Films , Nanchang 330031 , China
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29
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Mooshammer F, Sandner F, Huber MA, Zizlsperger M, Weigand H, Plankl M, Weyrich C, Lanius M, Kampmeier J, Mussler G, Grützmacher D, Boland JL, Cocker TL, Huber R. Nanoscale Near-Field Tomography of Surface States on (Bi 0.5Sb 0.5) 2Te 3. Nano Lett 2018; 18:7515-7523. [PMID: 30419748 DOI: 10.1021/acs.nanolett.8b03008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Three-dimensional topological insulators (TIs) have attracted tremendous interest for their possibility to host massless Dirac Fermions in topologically protected surface states (TSSs), which may enable new kinds of high-speed electronics. However, recent reports have outlined the importance of band bending effects within these materials, which results in an additional two-dimensional electron gas (2DEG) with finite mass at the surface. TI surfaces are also known to be highly inhomogeneous on the nanoscale, which is masked in conventional far-field studies. Here, we use near-field microscopy in the mid-infrared spectral range to probe the local surface properties of custom-tailored (Bi0.5Sb0.5)2Te3 structures with nanometer precision in all three spatial dimensions. Applying nanotomography and nanospectroscopy, we reveal a few-nanometer-thick layer of high surface conductivity and retrieve its local dielectric function without assuming any model for the spectral response. This allows us to directly distinguish between different types of surface states. An intersubband transition within the massive 2DEG formed by quantum confinement in the bent conduction band manifests itself as a sharp, surface-bound, Lorentzian-shaped resonance. An additional broadband background in the imaginary part of the dielectric function may be caused by the TSS. Tracing the intersubband resonance with nanometer spatial precision, we observe changes of its frequency, likely originating from local variations of doping or/and the mixing ratio between Bi and Sb. Our results highlight the importance of studying the surfaces of these novel materials on the nanoscale to directly access the local optical and electronic properties via the dielectric function.
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Affiliation(s)
- Fabian Mooshammer
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Fabian Sandner
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Markus A Huber
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Martin Zizlsperger
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Helena Weigand
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Markus Plankl
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Christian Weyrich
- Peter Grünberg Institut 9 , Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance , 52425 Jülich , Germany
| | - Martin Lanius
- Peter Grünberg Institut 9 , Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance , 52425 Jülich , Germany
| | - Jörn Kampmeier
- Peter Grünberg Institut 9 , Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance , 52425 Jülich , Germany
| | - Gregor Mussler
- Peter Grünberg Institut 9 , Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance , 52425 Jülich , Germany
| | - Detlev Grützmacher
- Peter Grünberg Institut 9 , Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance , 52425 Jülich , Germany
| | - Jessica L Boland
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
| | - Tyler L Cocker
- Department of Physics and Astronomy , Michigan State University , East Lansing , Michigan 48824 , United States
| | - Rupert Huber
- Department of Physics , University of Regensburg , 93040 Regensburg , Germany
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30
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Yu J, Liu C, Yuan K, Lu Z, Cheng Y, Li L, Zhang X, Jin P, Meng F, Liu H. Luminescence Mechanism of Carbon Dots by Tailoring Functional Groups for Sensing Fe 3+ Ions. Nanomaterials (Basel) 2018; 8:nano8040233. [PMID: 29649110 PMCID: PMC5923563 DOI: 10.3390/nano8040233] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/03/2018] [Accepted: 04/09/2018] [Indexed: 11/17/2022]
Abstract
In this paper, spherical carbon dots (CDs) with distinct compositions and surface states have been successfully synthesized by a facile microwave method. From the fluorescence spectra, several characteristic luminescence features have been observed: surface amino groups are dominant in the whole emission spectra centering at 445 nm, and the fingerprint emissions relevant to the impurity levels formed by some groups related to C and N elements, including C-C/C=C (intrinsic C), C-N (graphitic N), N-containing heterocycles (pyridine N) and C=O groups, are located around 305 nm, 355 nm, 410 nm, and 500 nm, respectively. Those fine luminescence features could be ascribed to the electron transition among various trapping states within the band structure caused by different chemical bonds in carbon cores, or functional groups attached to the CDs’ surfaces. According to the theoretical calculations and experimental results, a scheme of the band structure has been proposed to describe the positions of those trapping states within the band gap. Additionally, it has also been observed that the emission of CDs is sensitive to the concentration of Fe3+ ions with a linear relation in the range of Fe3+ concentration from 12.5 to 250 μM.
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Affiliation(s)
- Jingjing Yu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Chang Liu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Kang Yuan
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Zunming Lu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Yahui Cheng
- Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071, China.
| | - Lanlan Li
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Xinghua Zhang
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Peng Jin
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Fanbin Meng
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Hui Liu
- Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, the Institute for New Energy Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China.
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31
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Lynall D, Nair SV, Gutstein D, Shik A, Savelyev IG, Blumin M, Ruda HE. Surface State Dynamics Dictating Transport in InAs Nanowires. Nano Lett 2018; 18:1387-1395. [PMID: 29345949 DOI: 10.1021/acs.nanolett.7b05106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Because of their high aspect ratio, nanostructures are particularly susceptible to effects from surfaces such as slow electron trapping by surface states. However, nonequilibrium trapping dynamics have been largely overlooked when considering transport in nanoelectronic devices. In this study, we demonstrate the profound influence of dynamic trapping processes on transport in InAs nanowires through an investigation of the hysteretic and time-dependent behavior of the transconductance. We observe large densities (∼1013 cm-2) of slow surface traps and demonstrate the ability to control and permanently fix their occupation and charge through electrostatic manipulation by the gate potential followed by thermal deactivation by cryogenic cooling. Furthermore, we observe a transition from enhancement- to depletion-mode and a 400% change in field-effect mobility within the same device when the initial gate voltage and sweep rate are varied, revealing the severe impact of electrostatic history and dynamics on InAs nanowire field-effect transistors. A time-dependent model for nanowire transconductance based on nonequilibrium carrier population dynamics with thermally activated capture and emission was constructed and showed excellent agreement with experiments, confirming the effects to be a direct result of the dynamics of slow surface traps characterized by large thermal activation barriers (∼ 700 meV). This work reveals a clear and direct link between the electrical conductivity and the microscopic interactions of charged species with nanowire surfaces and highlights the necessity for considering dynamic properties of surface states in nanoelectronic devices.
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Affiliation(s)
- David Lynall
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - Selvakumar V Nair
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - David Gutstein
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Electrical and Computer Engineering, University of Toronto , 10 Kings College Road, Toronto, Ontario M5S 3G4, Canada
| | - Alexander Shik
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - Igor G Savelyev
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - Marina Blumin
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada
| | - Harry E Ruda
- Centre for Advanced Nanotechnology, University of Toronto , 170 College Street, Toronto, Ontario M5S 3E3, Canada
- Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada
- Department of Electrical and Computer Engineering, University of Toronto , 10 Kings College Road, Toronto, Ontario M5S 3G4, Canada
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China , Chengdu 610054, China
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32
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Nowakowska S, Mazzola F, Alberti MN, Song F, Voigt T, Nowakowski J, Wäckerlin A, Wäckerlin C, Wiss J, Schweizer WB, Broszio M, Polley C, Leandersson M, Fatayer S, Ivas T, Baljozovic M, Mousavi SF, Ahsan A, Nijs T, Popova O, Zhang J, Muntwiler M, Thilgen C, Stöhr M, Pasti IA, Skorodumova NV, Diederich F, Wells J, Jung TA. Adsorbate-Induced Modification of the Confining Barriers in a Quantum Box Array. ACS Nano 2018; 12:768-778. [PMID: 29272579 DOI: 10.1021/acsnano.7b07989] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Quantum devices depend on addressable elements, which can be modified separately and in their mutual interaction. Self-assembly at surfaces, for example, formation of a porous (metal-) organic network, provides an ideal way to manufacture arrays of identical quantum boxes, arising in this case from the confinement of the electronic (Shockley) surface state within the pores. We show that the electronic quantum box state as well as the interbox coupling can be modified locally to a varying extent by a selective choice of adsorbates, here C60, interacting with the barrier. In view of the wealth of differently acting adsorbates, this approach allows for engineering quantum states in on-surface network architectures.
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Affiliation(s)
- Sylwia Nowakowska
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Federico Mazzola
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology (NTNU) , Høgskoleringen 5, Realfagbygget D5-170, 7491 Trondheim, Norway
| | - Mariza N Alberti
- Laboratory of Organic Chemistry, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Fei Song
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Shanghai Institute of Applied Physics , Chinese Academy of Sciences, 201204 Shanghai, P. R. China
| | - Tobias Voigt
- Laboratory of Organic Chemistry, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Jan Nowakowski
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen, Switzerland
| | - Aneliia Wäckerlin
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Christian Wäckerlin
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen, Switzerland
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, 8600 Dübendorf, Switzerland
| | - Jérôme Wiss
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - W Bernd Schweizer
- Laboratory of Organic Chemistry, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Max Broszio
- Laboratory of Organic Chemistry, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Craig Polley
- MAX IV Laboratory, Lund University , P.O. Box 118, 22100 Lund, Sweden
| | - Mats Leandersson
- MAX IV Laboratory, Lund University , P.O. Box 118, 22100 Lund, Sweden
| | - Shadi Fatayer
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
- Departamento de Física Aplicada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas , Campinas 13083-859, Brazil
| | - Toni Ivas
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Milos Baljozovic
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen, Switzerland
| | - S Fatemeh Mousavi
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Aisha Ahsan
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thomas Nijs
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Olha Popova
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Jun Zhang
- Laboratory for Synchrotron Radiation - Condensed Matter, Paul Scherrer Institute , 5232 Villigen, Switzerland
| | - Matthias Muntwiler
- Laboratory for Synchrotron Radiation - Condensed Matter, Paul Scherrer Institute , 5232 Villigen, Switzerland
| | - Carlo Thilgen
- Laboratory of Organic Chemistry, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Meike Stöhr
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Igor A Pasti
- Faculty of Physical Chemistry, University of Belgrade , Studentski trg 12-16, 11158 Belgrade, Serbia
| | - Natalia V Skorodumova
- Department of Materials Science and Engineering, KTH - Royal Institute of Technology , Brinellvägen 23, 100 44 Stockholm, Sweden
- Department of Physics and Astronomy, Uppsala University , Box 516, 751 20 Uppsala, Sweden
| | - François Diederich
- Laboratory of Organic Chemistry, ETH Zürich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Justin Wells
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology (NTNU) , Høgskoleringen 5, Realfagbygget D5-170, 7491 Trondheim, Norway
| | - Thomas A Jung
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen, Switzerland
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Alexander-Webber JA, Groschner CK, Sagade AA, Tainter G, Gonzalez-Zalba MF, Di Pietro R, Wong-Leung J, Tan HH, Jagadish C, Hofmann S, Joyce HJ. Engineering the Photoresponse of InAs Nanowires. ACS Appl Mater Interfaces 2017; 9:43993-44000. [PMID: 29171260 DOI: 10.1021/acsami.7b14415] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report on individual-InAs nanowire optoelectronic devices which can be tailored to exhibit either negative or positive photoconductivity (NPC or PPC). The NPC photoresponse time and magnitude is found to be highly tunable by varying the nanowire diameter under controlled growth conditions. Using hysteresis characterization, we decouple the observed photoexcitation-induced hot electron trapping from conventional electric field-induced trapping to gain a fundamental insight into the interface trap states responsible for NPC. Furthermore, we demonstrate surface passivation without chemical etching which both enhances the field-effect mobility of the nanowires by approximately an order of magnitude and effectively eliminates the hot carrier trapping found to be responsible for NPC, thus restoring an "intrinsic" positive photoresponse. This opens pathways toward engineering semiconductor nanowires for novel optical-memory and photodetector applications.
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Affiliation(s)
- Jack A Alexander-Webber
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
| | - Catherine K Groschner
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
| | - Abhay A Sagade
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
- SRM Research Institute, Department of Physics & Nanotechnology, SRM University , Kattankulathur 603 203, India
| | - Gregory Tainter
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
| | | | - Riccardo Di Pietro
- Hitachi Cambridge Laboratory , JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Jennifer Wong-Leung
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University , Canberra, ACT 2601, Australia
| | - H Hoe Tan
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University , Canberra, ACT 2601, Australia
| | - Chennupati Jagadish
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University , Canberra, ACT 2601, Australia
| | - Stephan Hofmann
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
| | - Hannah J Joyce
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom
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Qin DD, He CH, Li Y, Trammel AC, Gu J, Chen J, Yan Y, Shan DL, Wang QH, Quan JJ, Tao CL, Lu XQ. Fe 2 PO 5 -Encapsulated Reverse Energetic ZnO/Fe 2 O 3 Heterojunction Nanowire for Enhanced Photoelectrochemical Oxidation of Water. ChemSusChem 2017; 10:2796-2804. [PMID: 28570775 DOI: 10.1002/cssc.201700501] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 04/20/2017] [Indexed: 06/07/2023]
Abstract
Zinc oxide is regarded as a promising candidate for application in photoelectrochemical water oxidation due to its higher electron mobility. However, its instability under alkaline conditions limits its application in a practical setting. Herein, we demonstrate an easily achieved wet-chemical route to chemically stabilize ZnO nanowires (NWs) by protecting them with a thin layer Fe2 O3 shell. This shell, in which the thickness can be tuned by varying reaction times, forms an intact interface with ZnO NWs, thus protecting ZnO from corrosion in a basic solution. The reverse energetic heterojunction nanowires are subsequently activated by introducing an amorphous iron phosphate, which substantially suppressed surface recombination as a passivation layer and improved photoelectrochemical performance as a potential catalyst. Compared with pure ZnO NWs (0.4 mA cm-2 ), a maximal photocurrent of 1.0 mA cm-2 is achieved with ZnO/Fe2 O3 core-shell NWs and 2.3 mA cm-2 was achieved for the PH3 -treated NWs at 1.23 V versus RHE. The PH3 low-temperature treatment creates a dual function, passivation and catalyst layer (Fe2 PO5 ), examined by X-ray photoelectron spectroscopy, TEM, photoelectrochemical characterization, and impedance measurements. Such a nano-composition design offers great promise to improve the overall performance of the photoanode material.
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Affiliation(s)
- Dong-Dong Qin
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Cai-Hua He
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Yang Li
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Antonio C Trammel
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, 92182, USA
| | - Jing Gu
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, 92182, USA
| | - Jing Chen
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Yong Yan
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, New Jersey, 07102, USA
| | - Duo-Liang Shan
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Qiu-Hong Wang
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Jing-Jing Quan
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
| | - Chun-Lan Tao
- School of Physical Science and Technology, Lanzhou University, Lanzhou, Gansu, 730000, P. R. China
| | - Xiao-Quan Lu
- Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, P. R. China
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Schendel V, Borca B, Pentegov I, Michnowicz T, Kraft U, Klauk H, Wahl P, Schlickum U, Kern K. Remotely Controlled Isomer Selective Molecular Switching. Nano Lett 2016; 16:93-97. [PMID: 26619213 DOI: 10.1021/acs.nanolett.5b02974] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nonlocal addressing-the "remote control"-of molecular switches promises more efficient processing for information technology, where fast speed of switching is essential. The surface state of the (111) facets of noble metals, a confined two-dimensional electron gas, provides a medium that enables transport of signals over large distances and hence can be used to address an entire ensemble of molecules simultaneously with a single stimulus. In this study we employ this characteristic to trigger a conformational switch in anthradithiophene (ADT) molecules by injection of hot carriers from a scanning tunneling microscope (STM) tip into the surface state of Cu(111). The carriers propagate laterally and trigger the switch in molecules at distances as far as 100 nm from the tip location. The switching process is shown to be long-ranged, fully reversible, and isomer selective, discriminating between cis and trans diastereomers, enabling maximum control.
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Affiliation(s)
- Verena Schendel
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Bogdana Borca
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Ivan Pentegov
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | | | - Ulrike Kraft
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Hagen Klauk
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Peter Wahl
- Max Planck Institute for Solid State Research, Stuttgart, Germany
- SUPA, School of Physics and Astronomy, University of St. Andrews , St. Andrews, Scotland, United Kingdom
| | - Uta Schlickum
- Max Planck Institute for Solid State Research, Stuttgart, Germany
| | - Klaus Kern
- Max Planck Institute for Solid State Research, Stuttgart, Germany
- Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Zhang C, Liu Y, Yuan X, Wang W, Liang S, Xiu F. Highly tunable Berry phase and ambipolar field effect in topological crystalline insulator Pb(1-x)Sn(x)Se. Nano Lett 2015; 15:2161-2167. [PMID: 25705997 DOI: 10.1021/acs.nanolett.5b00172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Recently, rock-salt IV-VI semiconductors, such as Pb(1-x)Sn(x)Se(Te) and SnTe, have been observed to host topological crystalline insulator (TCI) states. The nontrivial states have long been believed to exhibit ambipolar field effects and possess massive Dirac Fermions in two-dimension (2D) limit due to the surface hybridization. However, these exciting attributes of TCI remain previously inaccessible owing to the complicated control over composition and thickness. Here, we systematically investigate doping and thickness-induced topological phase transitions by electrical transport. We demonstrate the first evidence of the ambipolar properties in Pb(1-x)Sn(x)Se thin films. Surface gap opening is observed in 10 nm TCI originated from the strong finite-size effect. Importantly, magnetoconductance hosts a competition between weak antilocalization and weak localization, suggesting a strikingly tunable Berry phase evolution and strong electron-electron interaction. Our findings serve as a new probe to study electron behavior and pave the way for further exploring and manipulating this novel 2D TCI phase.
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Affiliation(s)
- Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics and ‡Collaborative Innovation Center of Advanced Microstructures, Fudan University , Shanghai 200433, China
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