Article
Materials Science, Ceramics
Kai Chen, Yachao Zhang, Jincheng Zhang, Xing Wang, Yixin Yao, Jinbang Ma, Yue Hao
Summary: By analyzing the growth modes of GaN films on AlN buffer layers with different thicknesses, a new growth model of GaN on AlN buffer was proposed in this study. Under optimal conditions, AlGaN/GaN/AlN heterostructures showed excellent performance.
CERAMICS INTERNATIONAL
(2022)
Article
Multidisciplinary Sciences
Jiabiao Chen, Zhaochao Liu, Xinyue Dong, Zhansheng Gao, Yuxuan Lin, Yuyu He, Yingnan Duan, Tonghuai Cheng, Zhengyang Zhou, Huixia Fu, Feng Luo, Jinxiong Wu
Summary: Ultrathin Bi2SiO5 crystals grown by chemical vapor deposition (CVD) serve as excellent gate dielectric layers for 2D semiconductors, exhibiting high dielectric constant and large band gap. Vertically grown Bi2SiO5 can be easily transferred onto other substrates, facilitating ideal van der Waals integration with few-layer MoS2.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Coatings & Films
O. Fesiienko, C. Petit-Etienne, M. Darnon, A. Soltani, H. Maher, E. Pargon
Summary: Gate patterning is crucial in the fabrication of metal oxide semiconductor high electron mobility transistor based on AlGaN/GaN heterostructure. This study evaluates the chemical changes and modifications of the AlGaN barrier layer induced by high and low ion energy plasma processes. The KOH postetching treatment effectively removes the AlGaNFx subsurface reactive layer and restores the surface properties of the AlGaN layer.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Engineering, Electrical & Electronic
Jiarui Guo, Yan Gu, Yushen Liu, Fangzhou Liang, Wei Chen, Feng Xie, Xifeng Yang, Weiying Qian, Xiangyang Zhang, Guoqing Chen, Guofeng Yang
Summary: This study designs a UV photodetector that utilizes a two-dimensional electron gas at the AlGaN/GaN interface with an AlGaN symmetrical interdigital structure. The AlGaN interdigital structure is fabricated with a Ti/Al/Ti/Au metal stack for ohmic contacts. The interdigital AlGaN/GaN heterostructure enhances the polarization electric field in the GaN absorption layer, facilitating the separation and transport of photogenerated carriers. The polarization-enhanced physical mechanism of the AlGaN/GaN 2DEG UV PD is explored through theoretical simulations. The designed UV PD exhibits a broadband characteristic with a response spectra from 300 to 365 nm and a cutoff wavelength of 365 nm, matching the bandgap wavelength of GaN. The normalized photocurrent-to-dark current ratio (NPDR) of 1.31 x 10(9) W-1 is measured at 10 V.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Chemistry, Physical
Fobao Huang, Jianghua Chen, Yiluo Ding, Wei Huang
Summary: The study explores the impact of the piezotronic effect and other effects on the two-dimensional electron gas (2DEG) in third-generation semiconductors. The results demonstrate that stress, induced by piezoelectric polarization, can effectively control the electron concentration of the 2DEG. Furthermore, the piezotronic effect can increase the density of states and enhance the Rashba spin-orbit coupling in wide-gap piezoelectric semiconductors.
Article
Physics, Applied
Yat Hon Ng, Zheyang Zheng, Li Zhang, Ruizi Liu, Tao Chen, Sirui Feng, Qiming Shao, Kevin J. Chen
Summary: This study investigates the hole distribution and transport in the p-GaN/AlGaN/GaN heterostructure through experimental measurements and simulations. The results show that the p-channel of this structure is composed of bulk holes in the p-GaN and a two-dimensional hole gas (2DHG) at the p-GaN/AlGaN interface. Both components contribute significantly to lateral p-type conduction at room temperature. The complementary temperature responses of these components enhance conductivity at both high and low temperatures.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
David Maria Tobaldi, Valentina Trimini, Arianna Creti, Mauro Lomascolo, Stefano Dicorato, Maria Losurdo, Adriana Passaseo, Vittorianna Tasco
Summary: The study successfully developed a remote plasma MOCVD method for epitaxial growth of high-quality GaN/AlGaN heterostructures. This method has lower growth temperature and uses remote plasma instead of ammonia, providing a cost-effective and green approach for high-quality heteroepitaxy.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Chemistry, Physical
Patrick Fiorenza, Emanuela Schiliro, Giuseppe Greco, Marilena Vivona, Marco Cannas, Filippo Giannazzo, Raffaella Lo Nigro, Fabrizio Roccaforte
Summary: The study investigates charge trapping phenomena in Al2O3 thin films grown on AlGaN/GaN heterostructures by ALD, using time-dependent C-V measurements. Results show competitive mechanisms for electron capture and emission in the Al2O3 film, as well as the presence of oxygen-related point defects with only a fraction being electrically active. These findings are valuable for understanding the thermal stability of trapping phenomena and potential applications in real devices.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
V. V. Solovyev, S. Schmult, L. Krueckeberg, A. Grosser, T. Mikolajick, I. V. Kukushkin
Summary: UV illumination has been shown to tune the 2D electron density in an ultra-pure GaN/Al0.25Ga0.75N heterojunction from 5.3 x 10^12 cm(-2) to 8.8 x 10^12 cm(-2), resulting in different behaviors in magnetotransport data and photoluminescence spectra. The distributions of electron densities and quantum lifetimes in each individual subband have been independently extracted, revealing an increase in quantum scattering time for electrons in the second subband compared to the ground state.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Sonachand Adhikari, Felipe Kremer, Mykhaylo Lysevych, Chennupati Jagadish, Hark Hoe Tan
Summary: GaN/AlGaN core-shell nanowires with various Al compositions have been grown on GaN nanowire array. The AlGaN shells have lower Al compositions than the gas phase input ratio. Defect-related luminescence has been observed in the AlGaN shells, with partial dislocations as the dominant defects. Growth of nonpolar m-plane AlxGa1-xN/AlyGa1-yN quantum wells on the sidewalls of the GaN nanowires shows excellent morphology and optical emission.
NANOSCALE HORIZONS
(2023)
Article
Chemistry, Physical
Anup Kumar Bera, Arun Singh Dev, Manik Kuila, Mukesh Ranjan, Pallavi Pandit, Matthias Schwartzkopf, Stephan Roth, Varimalla R. Reddy, Dileep Kumar
Summary: This study presents a new method of inducing large in-plane uniaxial magnetic anisotropy on nanopatterned rippled substrates through oblique angle deposition. The research focuses on the growth behavior and organization of adatoms in the form of columns, revealing the enhanced influence of shadowing effect.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
Julien Bassaler, Remi Comyn, Catherine Bougerol, Yvon Cordier, Farid Medjdoub, Philippe Ferrandis
Summary: This study focuses on the material investigation of an Al0.9Ga0.1N/GaN heterostructure, identifying various defects in the GaN channel that may contribute to reduced mobility and are linked to the quality of the channel interfaces.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Wanglong Wu, Chuankai Liu, Lixiang Han, Xiaozhou Wang, Jingbo Li
Summary: We have developed a novel high sensitive ultraviolet (UV) photodetector based on AlGaN/n-GaN/p-GaN heterostructure high electron mobility transistor (HEMT) on sapphire substrates. The photodetectors demonstrate ultra-low dark current and high light on/off ratio under UV LED irradiation. They also exhibit high photoresponse speed and overall high performance in terms of photoresponsivity, EQE, detectivity, and stability. The proposed photodetectors have the potential for applications in UV communication, Internet of Things, and medical treatment.
APPLIED SURFACE SCIENCE
(2023)
Article
Physics, Condensed Matter
Shixu Yang, Yang Wang, Gaoqiang Deng, Ye Yu, Yunfei Niu, Lidong Zhang, Jiaqi Yu, Chao Lu, Yuantao Zhang
Summary: In this study, AlGaN/GaN superlattices structures were grown on SiC substrates by MOCVD, investigating the influence of different parameters on their strain state and analyzing the strain relaxation mechanism.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Chemistry, Multidisciplinary
June-Heang Choi, Taehyun Park, Jaehyun Hur, Ho-Young Cha
Summary: An AlGaN/GaN heterostructure based hydrogen sensor was fabricated with a dual catalyst layer of ZnO-nanoparticles atop a Pd catalyst film. The sensor operated at room temperature without heating, thanks to the photocatalytic reaction of ZnO-NPs with ultraviolet illumination. It showed a sensing response of 25% for a hydrogen concentration of 4% at room temperature, with fast response and recovery times of 8 s and 11 s, respectively.
Article
Computer Science, Information Systems
Yuchen Li, Sen Huang, Xinhua Wang, Qimeng Jiang, Xinyu Liu
Summary: In this study, the temperature-dependent ON-state breakdown BVON of AlGaN/GaN HEMTs with an AlGaN back barrier was investigated using the gate current extraction technique. It was found that the impact ionization of acceptor-like traps is responsible for the ON-state breakdown in HEMTs when the 2DEG channel is marginally turned on. Additionally, the characteristic electric field of impact ionization was extracted and shown to have a U-shaped temperature dependence.
Article
Chemistry, Multidisciplinary
Junting Chen, Junlei Zhao, Sirui Feng, Li Zhang, Yan Cheng, Hang Liao, Zheyang Zheng, Xiaolong Chen, Zhen Gao, Kevin J. J. Chen, Mengyuan Hua
Summary: In this study, the GaN surface is converted into a GaON epitaxial nanolayer through a two-step oxidation-reconfiguration process, overcoming the vulnerability of the GaN surface and enhancing the stability and reliability of GaN-based devices. The GaON nanolayer derived from GaN possesses advantages such as a wide bandgap, high thermodynamic stability, and large valence band offset with a GaN substrate, which can be further utilized to improve the performance of GaN-based devices in various applications.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Kexin Deng, Xinhua Wang, Sen Huang, Qimeng Jiang, Haibo Yin, Jie Fan, Guanjun Jing, Yingjie Wang, Tiantian Luan, Ke Wei, Yingkui Zheng, Jingyuan Shi, Xinyu Liu
Summary: A PEALD-SiOxNy interfacial layer is used to suppress deep interface states and dielectric trapping in SiNx/GaN MIS structures. It protects the GaN surface from decomposing during the growth of SiNx dielectric and improves the interface characteristics.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Yan Cheng, Yat Hon Ng, Zheyang Zheng, Kevin J. Chen
Summary: Enhancement-mode (E-mode) submicron 0.45-μm p-GaN gate HEMTs on 200-mm high-resistivity-Si (HRS) substrates have been demonstrated with high uniformity and high overall combined performance for RF applications. The p-GaN gate HEMT exhibits positive threshold voltage, high transconductance, and high saturation current density. It also shows low OFF state leakage current, high breakdown voltage, and high cut-off frequencies. Additionally, it achieves high power output and efficiency at 5 GHz.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Yanjun Li, Shu Yang, Kai Liu, Kai Cheng, Kuang Sheng, Bo Shen
Summary: This article presents a low ON-resistance fully-vertical GaN-on-SiC Schottky barrier diode with a highly conductive buffer structure. The buffer structure includes a heavily doped Al0.25Ga0.75N layer on top of the SiC substrate and a graded Al0.25 -> 0Ga0.75 -> 1N layer at the GaN/Al0.25Ga0.75N interface. The optimized buffer structure results in a reduced specific ON-resistance of 0.96 mΩ cm². The fully-vertical GaN-on-SiC SBD demonstrates high forward current density, high current swing, an ideal Schottky interface, and enhanced reverse blocking voltage.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Nanoscience & Nanotechnology
Fengben Xi, Andreas Grenmyr, Jiayuan Zhang, Yi Han, Jin Hee Bae, Detlev Grutzmacher, Qing-Tai Zhao
Summary: Neuromorphic computing employs artificial synapses to transfer information between neurons. Conventional artificial synapses with homosynaptic plasticity face positive feedback loop problem, requiring synapses with heterosynaptic plasticity. This study presents complementary metal-oxide-semiconductor compatible artificial synapses based on FEMOD on silicon, allowing heterosynaptic plasticity with multi-functionalities, high endurance, low power consumption, and high speed. The proposed device structure performs multi-functions of biological synapse and Boolean logic, providing high potential for future large scale and low power neuromorphic computing applications.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Physics, Applied
Yanjun Li, Shu Yang, Fengwei Ji, Xi Tang, Kuang Sheng
Summary: This work investigates the conductivity modulation in vertical GaN-on-GaN PiN diodes under high current densities and its effect on surge current capability. By utilizing the direct-bandgap property of GaN, the junction temperature at different current densities is characterized through photo-luminescence and electro-luminescence measurements. The increase in current density leads to a rise in junction temperature and a shift in emission peaks. The enhanced conductivity modulation due to self-heating improves the ON-resistance, making it desirable for surge current capability. The study also demonstrates the potential of vertical GaN-on-GaN power devices in high electro-thermal-ruggedness applications based on the achieved surge energy density.
APPLIED PHYSICS LETTERS
(2023)
Article
Computer Science, Information Systems
Yuan Ji, Sen Huang, Qimeng Jiang, Ruizhe Zhang, Jie Fan, Haibo Yin, Yingkui Zheng, Xinhua Wang, Ke Wei, Xinyu Liu
Summary: The non-recessed ohmic contact resistance on ultrathin-barrier AlGaN/GaN heterostructure was effectively reduced to 0.16 Omega.mm using the 'ohmic-before-passivation' process. The recovery of 2-D Electron Gas adjacent to the ohmic contact was enhanced by a composite double-layer dielectric with AlN/SiNx passivation. Thermionic field emission was identified as the dominant ohmic contact mechanism. The optimized ohmic contact achieved low on-resistance and high current density, making it a promising strategy for optimizing low-voltage GaN-based power devices.
Article
Engineering, Electrical & Electronic
Omar Concepcion, Nicolaj B. Sogaard, Jin-Hee Bae, Yuji Yamamoto, Andreas T. Tiedemann, Zoran Ikonic, Giovanni Capellini, Qing-Tai Zhao, Detlev Gruetzmacher, Dan Buca
Summary: This paper presents the realization of high-quality pseudomorphic Ge1-xSnx layers with Sn content ranging from 6 at. % up to 15 at. % using isothermal processes. The N2 carrier gas flow is adjusted to obtain isothermal heterostructure designs suitable for quantum transport and spintronic devices.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Tao Chen, Zheyang Zheng, Sirui Feng, Li Zhang, Kevin J. Chen
Summary: A GaN-based non-volatile memory device with improved endurance, fast programming speed, and long retention time is proposed in this study. The endurance is improved by using a less destructive programming scheme based on back gate injection and reducing the doping concentration of the p-channel. The device can withstand over 1010 program/erase cycles and requires a -10V/200ns pulse for programming without compromising the retention time.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Sirui Feng, Hang Liao, Tao Chen, Junting Chen, Yan Cheng, Mengyuan Hua, Zheyang Zheng, Kevin J. Chen
Summary: The mechanism of carrier dynamics in the gate stack of a Schottky-type p-GaN gate double-channel GaN HEMT was investigated through the analysis of electroluminescence characteristics. It was discovered that the AlN insertion layer in the DC-HEMT acts as a blocking layer to prevent hole injection from the gate to the channel, creating a hole-storage effect that effectively suppresses channel-to-gate electron spillover under forward gate bias.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Shaocheng Li, Kuang Sheng, Shu Yang
Summary: In this study, the temperature-dependent dynamic ON-resistance (R_on) behaviors of GaN E-HEMTs with and without a p-GaN drain (PD) structure under both hard-switching (HS) and soft-switching (SS) were systematically studied and analyzed. The influences of temperature, OFF-state voltage stress, the PD structure, HS/SS, switching transients during HS, and ON-state current on dynamic R_on of GaN E-HEMTs were revealed. The findings indicate that higher temperature, higher OFF-state voltage stress, or larger ON-state current, particularly under HS, can enhance the dynamic performance of GaN E-HEMTs by facilitating the turn-on of the PD hetero-junction and enhancing hole injection.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Ho-Tin Tang, Henry Shu-Hung Chung, Kevin Jing Chen
Summary: An adaptive level-shift gate driver with indirect gate oxide health monitoring is proposed to suppress crosstalk of bridge-leg configured SiC MOSFETs. Gate leakage is found to be an appropriate precursor to reflect gate oxide degradation. The proposed gate driver uses a digitally controlled variable resistor to adjust the OFF-state gate-source voltage and regulate the peak OFF-state gate-source voltage to avoid shoot-through and reduce OFF-state voltage stress on the gate. Additionally, the gate oxide degradation is indirectly monitored by observing the change in the value of the variable resistor.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Christian Roemer, Nadine Dersch, Ghader Darbandy, Mike Schwarz, Yi Han, Qing-Tai Zhao, Benjamin Iniguez, Alexander Kloes
Summary: In this paper, a physics-based DC compact model for Schottky barrier field-effect transistors at deep cryogenic temperatures is proposed. The model incorporates simplified tunneling equations for calculating the field emission injection current at the device's Schottky barriers at temperatures above 0 K, and also introduces an empirical expression to account for resonant tunneling effects. The accuracy of the compact model is verified by comparing it with measurements on ultra-thin body and buried oxide SOI Schottky barrier field-effect transistors, showing its capability to capture the signature of resonant tunneling effects in transfer characteristics.
SOLID-STATE ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Meng Zhang, Yamin Zhang, Baikui Li, Shiwei Feng, Mengyuan Hua, Xi Tang, Jin Wei, Kevin J. Chen
Summary: In this study, a new SiC planar IGBT with oxide shield is proposed to achieve an improved trade-off between on-state voltage drop and maximum gate oxide electric field. Through TCAD simulations, it is found that the proposed SiC IGBT can provide a low VON and keep Eox-m at a small value by adopting a larger distance between neighboring p-bodies and using oxide shielding structures. In addition, the proposed SiC-IGBT exhibits better trade-off between turn-off energy loss and VON compared to the conventional SiC planar IGBT.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2023)
