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Xu L, Guo H, Tao J, Zavabeti A, Zhou Y, Zheng Y, Zhang R, Chen D. Effect of Fe Doping Profile on Current Collapse in GaN-based RF HEMTs. Chemistry 2024; 30:e202304100. [PMID: 38451027 DOI: 10.1002/chem.202304100] [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: 12/09/2023] [Revised: 03/07/2024] [Accepted: 03/07/2024] [Indexed: 03/08/2024]
Abstract
Using computer-aided design (TCAD) simulation, the impact of the Fe doping profile, including concentration, decay rate, and depth of the doping region on current-collapse magnitude (▵CC) in 0.5-μm gated GaN-based high electron mobility transistors (HEMTs) is systematically investigated. Accurate simulation models are established and developed to facilitate the fabrication of electronics. It is elucidated that the intricate interplay between trapping and de-trapping of Fe-related traps at the gate-drain edge is responsible for current collapse. The concentration and decay rate of the doping region have a more significant impact on current collapse than the depth. Increased trap state density near two-dimensional electron gas (2DEG) channel caused by deep-level acceptors would boost ▵CC. However, a minor dynamic reduction in 2DEG density (nT) induces a relatively small ▵CC. By adjusting the concentration, decay rate, and depth of the doping region, ▵CC of GaN-based Radio Frequency (RF) HEMTs can be reduced by approximately 50.3 %. The optimized distribution of Fe doping discussed in this work helps to prepare GaN-based RF HEMTs with a limited current collapse effect.
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Affiliation(s)
- Linling Xu
- Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Hui Guo
- Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Jiaqi Tao
- College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 211100, China
| | - Ali Zavabeti
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Yugang Zhou
- Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Youdou Zheng
- Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Rong Zhang
- Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Dunjun Chen
- Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China
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Pizzone M, Grimaldi MG, La Magna A, Rahmani N, Scalese S, Adam J, Puglisi RA. Study of the Molecule Adsorption Process during the Molecular Doping. Nanomaterials (Basel) 2021; 11:1899. [PMID: 34443729 DOI: 10.3390/nano11081899] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 06/25/2021] [Revised: 07/19/2021] [Accepted: 07/21/2021] [Indexed: 11/25/2022]
Abstract
Molecular Doping (MD) involves the deposition of molecules, containing the dopant atoms and dissolved in liquid solutions, over the surface of a semiconductor before the drive-in step. The control on the characteristics of the final doped samples resides on the in-depth study of the molecule behaviour once deposited. It is already known that the molecules form a self-assembled monolayer over the surface of the sample, but little is known about the role and behaviour of possible multiple layers that could be deposited on it after extended deposition times. In this work, we investigate the molecular surface coverage over time of diethyl-propyl phosphonate on silicon, by employing high-resolution morphological and electrical characterization, and examine the effects of the post-deposition surface treatments on it. We present these data together with density functional theory simulations of the molecules–substrate system and electrical measurements of the doped samples. The results allow us to recognise a difference in the bonding types involved in the formation of the molecular layers and how these influence the final doping profile of the samples. This will improve the control on the electrical properties of MD-based devices, allowing for a finer tuning of their performance.
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Werner F, Babbe F, Burkhart J, Spindler C, Elanzeery H, Siebentritt S. Interdiffusion and Doping Gradients at the Buffer/Absorber Interface in Thin-Film Solar Cells. ACS Appl Mater Interfaces 2018; 10:28553-28565. [PMID: 30062875 DOI: 10.1021/acsami.8b08076] [Citation(s) in RCA: 6] [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] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
An accurate determination of the net dopant concentration in photovoltaic absorbers is critical for understanding and optimizing solar cell performance. The complex device structure of multilayered thin-film solar cells poses challenges to determine the dopant concentration. Capacitance-voltage ( C- V) measurements of Cu(In,Ga)Se2 thin-film solar cells typically yield depth-dependent apparent doping profiles and are not consistent with Hall measurements of bare absorbers. We show that deep defects cannot fully explain these discrepancies. We instead find that the space charge region capacitance follows the model of a linearly graded junction in devices containing a CdS or Zn(O,S) buffer layer, indicating that elemental intermixing at the absorber/buffer interface alters the dopant concentration within the absorber. For absorbers covered with MgF2, C- V measurements indeed agree well with Hall measurements. Photoluminescence measurements of Cu(In,Ga)Se2 absorbers before and after deposition of a CdS layer provide further evidence for a significant reduction of the near-surface net dopant concentration in the presence of CdS. We thus demonstrate that interdiffusion at the absorber/buffer interface is a critical factor to consider in the correct interpretation of doping profiles obtained from C- V analysis in any multilayered solar cell and that the true bulk dopant concentration in thin-film devices might be considerably different.
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Affiliation(s)
- Florian Werner
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg
| | - Finn Babbe
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg
| | - Jan Burkhart
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg
| | - Conrad Spindler
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg
| | - Hossam Elanzeery
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg
| | - Susanne Siebentritt
- Laboratory for Photovoltaics, Physics and Materials Science Research Unit , University of Luxembourg , Rue du Brill 41 , L-4422 Belvaux , Luxembourg
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Chen HY, Lu HL, Chen JX, Zhang F, Ji XM, Liu WJ, Yang XF, Zhang DW. Low-Temperature One-Step Growth of AlON Thin Films with Homogenous Nitrogen- Doping Profile by Plasma-Enhanced Atomic Layer Deposition. ACS Appl Mater Interfaces 2017; 9:38662-38669. [PMID: 29039913 DOI: 10.1021/acsami.7b12262] [Citation(s) in RCA: 3] [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: 06/07/2023]
Abstract
The AlON film with homogeneous nitrogen-doping profile was grown by plasma-enhanced atomic layer deposition (PEALD) at low temperature. In this work, the precursors of the NH3 and the O2 were simultaneously introduced into the chamber during the PEALD growth at a relatively low temperature of 185 °C. It is found that the composition of the obtained film quickly changes from AlN to Al2O3 when a small amount of O2 is added. Thus, the NH3:O2 ratio should be maintained at a relatively high level (>85%) for realizing the AlON growth. Benefited from the growth method, the nitrogen can be doped evenly in the entire film. Moreover, the AlON films exhibit a lower surface roughness than the AlN as well as the Al2O3 ones. The Al 2p and N 1s X-ray photoelectron spectra show that the AlON film is composed of Al-N, Al-O, and N-Al-O bonds. Moreover, a three-layer construction of the AlON film is proposed through the Si 2p spectra analysis and reconfirmed by the transmission electron microscopy characterization. At last, the electrical and optical tests indicate that the AlON films prepared in this work can be employed as the gate dielectric in transistor application as well as the antireflection layer in photovoltaic application.
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Affiliation(s)
- Hong-Yan Chen
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
| | - Hong-Liang Lu
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
| | - Jin-Xin Chen
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
| | - Feng Zhang
- Key Laboratory of Semiconductor Material Sciences, Institute of Semiconductors, Chinese Academy of Sciences , Beijing 100083, China
| | - Xin-Ming Ji
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
| | - Wen-Jun Liu
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
| | - Xiao-Feng Yang
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
| | - David Wei Zhang
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University , Shanghai 200433, China
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Jafari MJ, Liu J, Engquist I, Ederth T. Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells. ACS Appl Mater Interfaces 2017; 9:2747-2757. [PMID: 28032741 DOI: 10.1021/acsami.6b14162] [Citation(s) in RCA: 3] [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: 06/06/2023]
Abstract
An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.
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Affiliation(s)
- Mohammad Javad Jafari
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University , Linköping SE-581 83, Sweden
| | - Jiang Liu
- Department of Science and Technology, Campus Norrköping, Linköping University , Norrköping SE-601 74, Sweden
| | - Isak Engquist
- Department of Science and Technology, Campus Norrköping, Linköping University , Norrköping SE-601 74, Sweden
| | - Thomas Ederth
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University , Linköping SE-581 83, Sweden
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Chou LW, Boyuk DS, Filler MA. Optically abrupt localized surface plasmon resonances in si nanowires by mitigation of carrier density gradients. ACS Nano 2015; 9:1250-1256. [PMID: 25612192 DOI: 10.1021/nn504974z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [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
Spatial control of carrier density is critical for engineering and exploring the interactions of localized surface plasmon resonances (LSPRs) in nanoscale semiconductors. Here, we couple in situ infrared spectral response measurements and discrete dipole approximation (DDA) calculations to show the impact of axially graded carrier density profiles on the optical properties of mid-infrared LSPRs supported by Si nanowires synthesized by the vapor-liquid-solid technique. The region immediately adjacent to each intentionally encoded resonator (i.e., doped segment) can exhibit residual carrier densities as high as 10(20) cm(-3), which strongly modifies both near- and far-field behavior. Lowering substrate temperature during the spacer segment growth reduces this residual carrier density and results in a spectral response that is indistinguishable from nanowires with ideal, atomically abrupt carrier density profiles. Our experiments have important implications for the control of near-field plasmonic phenomena in semiconductor nanowires, and demonstrate methods for determining and controlling axial dopant profile in these systems.
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Affiliation(s)
- Li-Wei Chou
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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