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Cottom J, Hückmann L, Olsson E, Meyer J. From Jekyll to Hyde and Beyond: Hydrogen's Multifaceted Role in Passivation, H-Induced Breakdown, and Charging of Amorphous Silicon Nitride. J Phys Chem Lett 2024; 15:840-848. [PMID: 38235960 PMCID: PMC10823530 DOI: 10.1021/acs.jpclett.3c03376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/05/2024] [Accepted: 01/09/2024] [Indexed: 01/19/2024]
Abstract
In semiconductor devices, hydrogen has traditionally been viewed as a panacea for defects, being adept at neutralizing dangling bonds and consequently purging the related states from the band gap. With amorphous silicon nitride (a-Si3N4)─a material critical for electronic, optical, and mechanical applications─this belief holds true as hydrogen passivates both silicon and nitrogen dangling bonds. However, there is more to the story. Our density functional theory calculations unveil hydrogen's multifaceted role upon incorporation in a-Si3N4. On the "Jekyll" side, hydrogen atoms are indeed restorative, healing coordination defects in a-Si3N4. However, "Hyde" emerges as hydrogen induces Si-N bond breaking, particularly in strained regions of the amorphous network. Beyond these dual roles, our study reveals an intricate balance between hydrogen defect centers and intrinsic charge traps that already exist in pristine a-Si3N4: the excess charges provided by the H atoms result in charging of the a-Si3N4 dielectric layer.
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Affiliation(s)
- Jonathon Cottom
- Leiden
Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Lukas Hückmann
- Leiden
Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Emilia Olsson
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
- Institute
for Theoretical Physics, University of Amsterdam, Postbus 94485, 1090 GL Amsterdam, The Netherlands
| | - Jörg Meyer
- Leiden
Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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2
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Qiu C, Song Y, Deng HX, Wei SH. Dual-Level Enhanced Nonradiative Carrier Recombination in Wide-Gap Semiconductors: The Case of Oxygen Vacancy in SiO 2. J Am Chem Soc 2023. [PMID: 37916909 DOI: 10.1021/jacs.3c09808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
The conventional single-defect-mediated Shockley-Read-Hall model suggests that the nonradiative carrier recombination rate in wide-band gap (WBG) semiconductors would be negligible because the single-defect level is expected to be either far from valence-band-maximum (VBM) or conduction-band-minimum (CBM), or both. However, this model falls short of elucidating the substantial nonradiative recombination phenomena often observed experimentally across various WBG semiconductors. Owing to more localized nature of defect states inherent to WBG semiconductors, when the defect charge state changes, there is a pronounced structural relaxation around the local defect site. This suggests that a defect at each charge state may exhibit a few distinct local configurations, namely, a stable configuration and a few metastable/transit state configurations. Consequently, a dual-level nonradiative recombination model should more realistically exist in WBG semiconductors. In this model, through the dual-level mechanism, electron and hole trap levels are different from each other and could be closer to the CBM for the electron trap and closer to the VBM for the hole trap, respectively; therefore, this significantly increases the corresponding electron and hole capture rates, enhancing the overall process of nonradiative recombination, and explains the experimental observations. In this work, taking technically important SiO2 as an illustrative example, we introduce the dual-level mechanism to elucidate the mechanism of nonradiative carrier recombination in WBG semiconductors. Our findings demonstrated strong alignment with available experimental data, reinforcing the robustness of our proposed dual-level model. Our fundamental understanding, therefore, provides a clear physical picture of the issue and can also be applied to predict the defect-related nonradiative carrier recombination characteristics in other WBG materials.
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Affiliation(s)
- Chen Qiu
- Beijing Computational Science Research Center, Beijing 100094, China
| | - Yu Song
- Beijing Computational Science Research Center, Beijing 100094, China
- College of Physics and Electronic Information Engineering, Neijiang Normal University, Neijiang 641112, China
| | - Hui-Xiong Deng
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences & Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100083, China
| | - Su-Huai Wei
- Beijing Computational Science Research Center, Beijing 100094, China
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Shalabny A, Buonocore F, Celino M, Shalev G, Zhang L, Wu W, Li P, Arbiol J, Bashouti MY. Semiconductivity Transition in Silicon Nanowires by Hole Transport Layer. NANO LETTERS 2020; 20:8369-8374. [PMID: 33104366 DOI: 10.1021/acs.nanolett.0c03543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The surface of nanowires is a source of interest mainly for electrical prospects. Thus, different surface chemical treatments were carried out to develop recipes to control the surface effect. In this work, we succeed in shifting and tuning the semiconductivity of a Si nanowire-based device from n- to p-type. This was accomplished by generating a hole transport layer at the surface by using an electrochemical reaction-based nonequilibrium position to enhance the impact of the surface charge transfer. This was completed by applying different annealing pulses at low temperature (below 400 °C) to reserve the hydrogen bonds at the surface. After each annealing pulse, the surface was characterized by XPS, Kelvin probe measurements, and conductivity measured by FET based on a single Si NW. The mechanism and conclusion were supported experimentally and theoretically. To this end, this strategy has been demonstrated as an essential tool which could pave a new road for regulating semiconductivity and for other low-dimensional nanomaterials.
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Affiliation(s)
- Awad Shalabny
- Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshset Ben-Gurion, Building 26, Beer-Sheva 8499000, Israel
| | | | - Massimo Celino
- ENEA, C. R. Casaccia, via Anguillarese 301, 00123 Rome, Italy
| | - Gil Shalev
- School of Electrical & Computer Engineering, Ben-Gurion University of the Negev, POB653, Beer-Sheva 8410501, Israel
| | - Lu Zhang
- School of Advanced Materials and Nanotechnology, Interdisciplinary Research Center of Smart Sensors, Xidian University, Shaanxi 710126, P.R. China
| | - Weiwei Wu
- School of Advanced Materials and Nanotechnology, Interdisciplinary Research Center of Smart Sensors, Xidian University, Shaanxi 710126, P.R. China
| | - Peixian Li
- School of Advanced Materials and Nanotechnology, Interdisciplinary Research Center of Smart Sensors, Xidian University, Shaanxi 710126, P.R. China
| | - Jordi Arbiol
- Institució Catalana de Recerca i Estudis Avançats (ICREA) and Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, CAT, Spain
| | - Muhammad Y Bashouti
- Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshset Ben-Gurion, Building 26, Beer-Sheva 8499000, Israel
- The IISe-Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, POB653, Building 51, Beer-Sheva 8410501, Israel
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4
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Chen T, Lu Y, Sheng Y, Shu Y, Li X, Chang RJ, Bhaskaran H, Warner JH. Ultrathin All-2D Lateral Graphene/GaS/Graphene UV Photodetectors by Direct CVD Growth. ACS APPLIED MATERIALS & INTERFACES 2019; 11:48172-48178. [PMID: 31833364 DOI: 10.1021/acsami.9b11984] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
UV-sensitive lateral all-two-dimensional (2D) photodetecting devices are produced by growing the large band gap layered GaS between graphene electrode pairs directly using chemical vapor deposition methods. The use of prepatterned graphene electrode pairs on the Si wafer enables more than 200 devices to be fabricated simultaneously. We show that the surface chemistry of the substrate during GaS leads to selective growth in graphene gaps, forming the lateral heterostructures, rather than on the surface of graphene. The graphene/GaS/graphene lateral photodetecting devices are demonstrated to be sensitive to UV light only, with no measurable response to visible light. Furthermore, we demonstrate UV-band discrimination in photosensing, with measured photocurrents only produced for middle-UV and not for near-UV wavelength regions. The detection limit could reach down to 2.61 μW/cm2 with a photoresponsivity as high as 11.7 A/W and a photo gain of 53.7 under 270 nm excitation. Gate-dependent modulation of the photocurrent is also demonstrated. The photodetectors exhibit long-term stability and reproducible ON-OFF switching behavior, with a response time lower than 60 ms. These results provide insights into how ultrathin UV sensing devices can be created using only 2D materials by exploiting large band gap 2D semiconductors such as GaS.
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Affiliation(s)
- Tongxin Chen
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Yang Lu
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Yuewen Sheng
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Yu Shu
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Xuan Li
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Ren-Jie Chang
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Harish Bhaskaran
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
| | - Jamie H Warner
- Department of Materials , University of Oxford , Parks Road , Oxford OX1 3PH , United Kingdom
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Stampfer B, Zhang F, Illarionov YY, Knobloch T, Wu P, Waltl M, Grill A, Appenzeller J, Grasser T. Characterization of Single Defects in Ultrascaled MoS 2 Field-Effect Transistors. ACS NANO 2018; 12:5368-5375. [PMID: 29878746 DOI: 10.1021/acsnano.8b00268] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
MoS2 has received a lot of attention lately as a semiconducting channel material for electronic devices, in part due to its large band gap as compared to that of other 2D materials. Yet, the performance and reliability of these devices are still severely limited by defects which act as traps for charge carriers, causing severely reduced mobilities, hysteresis, and long-term drift. Despite their importance, these defects are only poorly understood. One fundamental problem in defect characterization is that due to the large defect concentration only the average response to bias changes can be measured. On the basis of such averaged data, a detailed analysis of their properties and identification of particular defect types are difficult. To overcome this limitation, we here characterize single defects on MoS2 devices by performing measurements on ultrascaled transistors (∼65 × 50 nm) which contain only a few defects. These single defects are characterized electrically at varying gate biases and temperatures. The measured currents contain random telegraph noise, which is due to the transfer of charge between the channel of the transistors and individual defects, visible only due to the large impact of a single elementary charge on the local electrostatics in these small devices. Using hidden Markov models for statistical analysis, we extract the charge capture and emission times of a number of defects. By comparing the bias-dependence of the measured capture and emission times to the prediction of theoretical models, we provide simple rules to distinguish oxide traps from adsorbates on these back-gated devices. In addition, we give simple expressions to estimate the vertical and energetic positions of the defects. Using the methods presented in this work, it is possible to locate the sources of performance and reliability limitations in 2D devices and to probe defect distributions in oxide materials with 2D channel materials.
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Affiliation(s)
- Bernhard Stampfer
- Institute for Microelectronics (TU Wien) , Gusshausstrasse 27-29 , 1040 Vienna , Austria
| | - Feng Zhang
- Purdue University , 1205 West State Street , West Lafayette , Indiana 47907 , United States
| | - Yury Yuryevich Illarionov
- Institute for Microelectronics (TU Wien) , Gusshausstrasse 27-29 , 1040 Vienna , Austria
- Ioffe Physical-Technical Institute , Polytechnicheskaya 26 , 194021 St-Petersburg , Russia
| | - Theresia Knobloch
- Institute for Microelectronics (TU Wien) , Gusshausstrasse 27-29 , 1040 Vienna , Austria
| | - Peng Wu
- Purdue University , 1205 West State Street , West Lafayette , Indiana 47907 , United States
| | - Michael Waltl
- Institute for Microelectronics (TU Wien) , Gusshausstrasse 27-29 , 1040 Vienna , Austria
| | - Alexander Grill
- Institute for Microelectronics (TU Wien) , Gusshausstrasse 27-29 , 1040 Vienna , Austria
| | - Joerg Appenzeller
- Purdue University , 1205 West State Street , West Lafayette , Indiana 47907 , United States
| | - Tibor Grasser
- Institute for Microelectronics (TU Wien) , Gusshausstrasse 27-29 , 1040 Vienna , Austria
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6
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Strand J, Kaviani M, Gao D, El-Sayed AM, Afanas'ev VV, Shluger AL. Intrinsic charge trapping in amorphous oxide films: status and challenges. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:233001. [PMID: 29692368 DOI: 10.1088/1361-648x/aac005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We review the current understanding of intrinsic electron and hole trapping in insulating amorphous oxide films on semiconductor and metal substrates. The experimental and theoretical evidences are provided for the existence of intrinsic deep electron and hole trap states stemming from the disorder of amorphous metal oxide networks. We start from presenting the results for amorphous (a) HfO2, chosen due to the availability of highest purity amorphous films, which is vital for studying their intrinsic electronic properties. Exhaustive photo-depopulation spectroscopy measurements and theoretical calculations using density functional theory shed light on the atomic nature of electronic gap states responsible for deep electron trapping observed in a-HfO2. We review theoretical methods used for creating models of amorphous structures and electronic structure calculations of amorphous oxides and outline some of the challenges in modeling defects in amorphous materials. We then discuss theoretical models of electron polarons and bi-polarons in a-HfO2 and demonstrate that these intrinsic states originate from low-coordinated ions and elongated metal-oxygen bonds in the amorphous oxide network. Similarly, holes can be captured at under-coordinated O sites. We then discuss electron and hole trapping in other amorphous oxides, such as a-SiO2, a-Al2O3, a-TiO2. We propose that the presence of low-coordinated ions in amorphous oxides with electron states of significant p and d character near the conduction band minimum can lead to electron trapping and that deep hole trapping should be common to all amorphous oxides. Finally, we demonstrate that bi-electron trapping in a-HfO2 and a-SiO2 weakens Hf(Si)-O bonds and significantly reduces barriers for forming Frenkel defects, neutral O vacancies and O2- ions in these materials. These results should be useful for better understanding of electronic properties and structural evolution of thin amorphous films under carrier injection conditions.
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Affiliation(s)
- Jack Strand
- Department of Physics, University College London, Gower Street, London WC1E 6BT, United Kingdom
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7
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Yun J, Cho YB, Jang W, Lee JG, Shin SJ, Han SH, Lee Y, Chung TD. Dielectric Breakdown and Post-Breakdown Dissolution of Si/SiO 2 Cathodes in Acidic Aqueous Electrochemical Environment. Sci Rep 2018; 8:1911. [PMID: 29382915 PMCID: PMC5789982 DOI: 10.1038/s41598-018-20247-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/10/2018] [Indexed: 11/17/2022] Open
Abstract
Understanding the conducting mechanisms of dielectric materials under various conditions is of increasing importance. Here, we report the dielectric breakdown (DB) and post-breakdown mechanism of Si/SiO2, a widely used semiconductor and dielectric, in an acidic aqueous electrochemical environment. Cathodic breakdown was found to generate conduction spots on the Si/SiO2 surface. Using scanning electrochemical microscopy (SECM), the size and number of conduction spots are confirmed to increase from nanometer to micrometer scale during the application of negative voltage. The morphologies of these conduction spots reveal locally recessed inverted-pyramidal structures with exposed Si{111} sidewalls. The pits generation preceded by DB is considered to occur via cathodic dissolution of Si and exfoliation of SiO2 that are induced by local pH increases due to the hydrogen evolution reaction (HER) at the conduction spots. The HER at the conduction spots is more sluggish due to strongly hydrogen-terminated Si{111} surfaces.
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Affiliation(s)
- Jeongse Yun
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yun-Bin Cho
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Woohyuk Jang
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jae Gyeong Lee
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Samuel Jaeho Shin
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seok Hee Han
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Youngmi Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea.
| | - Taek Dong Chung
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea. .,Advanced Institutes of Convergence Technology, Suwon-si, Gyeonggi-do, 16229, Republic of Korea.
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Munde MS, Gao DZ, Shluger AL. Diffusion and aggregation of oxygen vacancies in amorphous silica. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:245701. [PMID: 28504974 DOI: 10.1088/1361-648x/aa6f9a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Using density functional theory (DFT) calculations, we investigated oxygen vacancy diffusion and aggregation in relation to dielectric breakdown in amorphous silicon dioxide (a-SiO2). Our calculations indicate the existence of favourable sites for the formation of vacancy dimers and trimers in the amorphous network with maximum binding energies of approximately 0.13 eV and 0.18 eV, respectively. However, an average energy barrier height for neutral vacancy diffusion is found to be about 4.6 eV, rendering this process unfeasible. At Fermi level positions above 6.4 eV with respect to the top of the valence band, oxygen vacancies can trap up to two extra electrons. Average barriers for the diffusion of negative and double negatively charged vacancies are found to be 2.7 eV and 2.0 eV, respectively. These barriers are higher than or comparable to thermal ionization energies of extra electrons from oxygen vacancies into the conduction band of a-SiO2. In addition, we discuss the competing pathways for electron trapping in oxygen deficient a-SiO2 caused by the existence of intrinsic electron traps and oxygen vacancies. These results provide new insights into the role of oxygen vacancies in degradation and dielectric breakdown in amorphous silicon oxides.
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Affiliation(s)
- Manveer S Munde
- Department of Physics and Astronomy, University College London Gower Street, London WC1E 6BT, United Kingdom
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