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Dong X, Hou Y, Deng C, Wu J, Fu H. Bi 3O 2.5Se 2: a two-dimensional high-mobility polar semiconductor with large interlayer and interfacial charge transfer. NANOSCALE 2024. [PMID: 38973699 DOI: 10.1039/d4nr01758g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Two-dimensional semiconductors with large intrinsic polarity are highly attractive for applications in high-speed electronics, ultrafast and highly sensitive photodetectors and photocatalysis. However, previous studies mainly focus on neutral layered polar 2D materials with limited vertical dipoles and electrostatic potential difference (typically <1.5 eV). Here, using the first-principles calculations, we systematically investigated the polarity of few-layer Bi3O2.5Se2 semiconductors with ultrahigh predicted room-temperature carrier mobility (1790 cm2 V-1 s-1 for the monolayer). Thanks to its unique non-neutral layered structure, few-layer Bi3O2.5Se2 contributes to a substantial interlayer charge transfer (>0.5 e-) and almost the highest electrostatic potential difference (ΔΦ) of ∼4 eV among the experimentally attainable 2D layered materials. More importantly, positioning graphene on different charged layers ([Bi2O2.5]+ or [BiSe2]-) switches the charge transfer direction, inducing selective n-doping or p-doping. Furthermore, we can use polar Bi3O2.5Se2 as an exemplary assisted gate to gain additional holes or electrons except for the external electric field, thus breaking the traditional limitations of gate tunability (∼1014 cm-2) observed in experimental settings. Our work not only expands the family of polar 2D semiconductors, but also makes a conceptual advance on using them as an assisted gate in transistors.
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Affiliation(s)
- Xinyue Dong
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, P. R. China.
| | - Yameng Hou
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, P. R. China.
| | - Chaoyue Deng
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, P. R. China.
| | - Jinxiong Wu
- Tianjin Key Lab for Rare Earth Materials and Applications, Center for Rare Earth and Inorganic Functional Materials, Smart Sensor Interdisciplinary Science Center, School of Materials Science and Engineering, Nankai University, Tianjin 300350, P. R. China.
| | - Huixia Fu
- Center of Quantum Materials and Devices, College of Physics, Chongqing University, Chongqing 401331, P. R. China.
- Chongqing Key Laboratory for Strongly Coupled Physics, Chongqing University, Chongqing 401331, P. R. China
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Xu Y, Li D, Sun H, Xu H, Li P. Comprehensive understanding of electron mobility and superior performance in sub-10 nm DG ML tetrahex-GeC 2 n-type MOSFETs. Phys Chem Chem Phys 2024; 26:4284-4297. [PMID: 38231547 DOI: 10.1039/d3cp05327j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
In this study, we have investigated the electron mobility of monolayered (ML) tetrahex-GeC2 by solving the linearized Boltzmann transport equation (BTE) with the normalized full-band relaxation time approximation (RTA) using density functional theory (DFT). Contrary to what the deformation potential theory (DPT) suggested, the ZA acoustic mode was determined to be the most restrictive for electron mobility, not the LA mode. The electron mobility at 300 K is 803 cm2 (V s)-1, exceeding the 400 cm2 (V s)-1 of MoS2 which was calculated using the same method and measured experimentally. The ab initio quantum transport simulations were performed to assess the performance limits of sub-10 nm DG ML tetrahex-GeC2 n-type MOSFETs, including gate lengths (Lg) of 3 nm, 5 nm, 7 nm, and 9 nm, with the underlap (UL) effect considered for the first two. For both high-performance (HP) and low-power (LP) applications, their on-state currents (Ion) can meet the requirements of similar nodes in the ITRS 2013. In particular, the Ion is more remarkable for HP applications than that of the extensively studied MoS2. For LP applications, the Ion values at Lg of 7 and 9 nm surpass those of arsenene, known for having the largest Ion among 2D semiconductors. Subthreshold swings (SSs) as low as 69/53 mV dec-1 at an Lg of 9 nm were observed for HP/LP applications, and 73 mV dec-1 at an Lg of 5 nm for LP applications, indicating the excellent gate control capability. Moreover, the delay time τ and power dissipation (PDP) at Lg values of 3 nm, 5 nm, 7 nm, and 9 nm are all below the upper limits of the ITRS 2013 HP/LP proximity nodes and are comparable to or lower than those of typical 2D semiconductors. The sub-10 nm DG ML tetrahex-GeC2 n-type MOSFETs can be down-scaled to 9 nm and 5 nm for HP and LP applications, respectively, displaying desirable Ion, delay time τ, and PDP in the ballistic limit, making them a potential choice for sub-10 nm transistors.
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Affiliation(s)
- Yuehua Xu
- School of Microelectronics and Control Engineering, Changzhou University, Changzhou 213164, Jiangsu, China.
| | - Daqing Li
- School of Microelectronics and Control Engineering, Changzhou University, Changzhou 213164, Jiangsu, China.
| | - He Sun
- School of Microelectronics and Control Engineering, Changzhou University, Changzhou 213164, Jiangsu, China.
| | - Haowen Xu
- School of Microelectronics and Control Engineering, Changzhou University, Changzhou 213164, Jiangsu, China.
| | - Pengfei Li
- Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
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Xie W, Pang J, Yang J, Kuang X, Mao A. Highly-efficient heterojunction solar cells based on 2D Janus transition-metal nitride halide (TNH) monolayers with ultrahigh carrier mobility. NANOSCALE 2023; 15:18328-18336. [PMID: 37921002 DOI: 10.1039/d3nr03417h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Symmetry breaking has a crucial effect on electronic band structure and subsequently affects the light-absorption coefficient of monolayers. We systematically report a family of two-dimensional (2D) Janus transition-metal nitride halides (TNHs, T = Ti, Zr, Hf, Fe, Pd, Pt, Os, and Re; H = Cl and F) with breaking of both in-plane and out-of-plane structural symmetry. The dynamical, thermal and mechanical stabilities are calculated to check the stability of the Janus TNHs. The electric properties of ten TNHs are studied via the HSE06+SOC method and the band gaps range from 0.93 eV (PdNCl) to 4.74 eV (HfNCl). Desirable light adsorption coefficients of up to 105 cm-1 are obtained for the Janus TNHs with no central symmetry. The Janus OsNCl monolayer shows excellent electrical transport properties and ultrahigh carrier mobility (104 cm2 V-1 s-1). Heterojunctions formed by stacking two Janus TNH monolayers are further investigated for solar cell applications. Eight of the heterojunctions have type-II band alignments. Surprisingly, the OsNCl/FeNCl heterojunction has a power conversion efficiency (PCE) of 23.45%, which is a larger value compared to the PCE of GeSe/SnSe heterostructures (21.47%). The optical properties and the built-in electric field of the OsNCl/FeNCl heterojunction are investigated. These results indicate that the stable Janus TNH monolayers have potential applications in photoelectric devices, and the vertical heterojunctions can be used in solar cells.
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Affiliation(s)
- Wanying Xie
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China.
| | - Jiafei Pang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China.
| | - Jinni Yang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China.
| | - Xiaoyu Kuang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China.
| | - Aijie Mao
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China.
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Wang J, Lu J, Zhao X, Hu G, Yuan X, Qi S, Ren J. A theoretical study of novel orthorhombic group-IVB nitride halide monolayers for photocatalytic overall water splitting. Phys Chem Chem Phys 2023; 25:28807-28813. [PMID: 37850498 DOI: 10.1039/d3cp03826b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
Hydrogen energy is very important as a new clean energy source to combat the growing environmental problems. In this regard, novel photocatalyst materials for water splitting have a wide range of applications. Using first principles calculations, we theoretically studied three orthorhombic group-IVB nitride halide monolayers, Hf2N2Br2, Janus HfZrN2Br2 and Janus Hf2N2ClBr. The energy, dynamic and thermal stabilities are demonstrated for all three monolayers. Using the HSE hybrid functional, the calculations reveal that they are direct band gap semiconductors with suitable band edge positions, good optical absorptions, and anisotropic carrier mobilities, which makes them promising for water splitting applications. Importantly, the photogenerated carriers provide enough driving force to trigger the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) within wide pH ranges, and then overall water splitting can be achieved spontaneously. We conclude that orthorhombic group-IVB nitride halide monolayers have potential applications in photocatalytic nanodevices.
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Affiliation(s)
- Jiali Wang
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
| | - Jiajun Lu
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
| | - Xiuwen Zhao
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
| | - Guichao Hu
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
| | - Xiaobo Yuan
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
| | - Siyun Qi
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
| | - Junfeng Ren
- School of Physics and Electronics, Shandong Normal University, Jinan, 250358, China.
- Shandong Provincial Engineering and Technical Center of Light Manipulations & Institute of Materials and Clean Energy, Shandong Normal University, Jinan 250358, China
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Yuan M, Tan R, Li M, Jin C, Jing T, Sun Q. Tunable magnetocrystalline anisotropy of two-dimensional Fe 3GeTe 2 with adsorbed 5d-transition metal. Phys Chem Chem Phys 2022; 24:21470-21476. [PMID: 36048558 DOI: 10.1039/d2cp02083a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The demand for ultra-compact spintronic devices with lower energy consumption and higher storage density requires two-dimensional (2D) magnetic materials with tunable magnetocrystalline anisotropy (MCA) energy. Employing first-principles calculations, we have investigated the influence of W atom adsorption and biaxial strain on the magnetic properties of layered Fe3GeTe2. We demonstrate that the adsorption mode and applied strain play a critical role in determining their MCA. The Fe3GeTe2 adsorbed with W atoms undergoes a change in spin reorientation from out-of-plane to in-plane magnetization, yielding a colossal MCA up to -13.112 erg cm-2. The dominant contribution to these unexpected changes mainly arises from the W atoms with emerged magnetism and large SOC. Moreover, our results reveal distinct strain-driven modulation behaviors of the MCA in different adsorption configurations. The underlying atomistic mechanism mainly involves the alteration of various W-derived 5d-orbital states under the strain effect, leading to competitive changes of the corresponding spin-orbit coupling energies between the spin-parallel and spin-flip channels. Our findings not only provide useful guidance in optimizing the MCA performance of 2D magnetic crystals but also highlight the potential of W-adsorbed Fe3GeTe2 in the applications of new-generation magnetic memory storage devices.
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Affiliation(s)
- Miaojia Yuan
- School of Science, Shandong Jianzhu University, Jinan, Shandong, 250101, China.
| | - Ruishan Tan
- School of Science, Shandong Jianzhu University, Jinan, Shandong, 250101, China.
| | - Mengmeng Li
- School of Science, Shandong Jianzhu University, Jinan, Shandong, 250101, China.
| | - Cui Jin
- School of Science, Shandong Jianzhu University, Jinan, Shandong, 250101, China.
| | - Tao Jing
- College of Science, Kaili University, Kaili, Guizhou, 556011, China
| | - Qilong Sun
- School of Science, Shandong Jianzhu University, Jinan, Shandong, 250101, China.
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