Article
Physics, Applied
Zesheng Lv, Jiabing Lu, Haoming Xu, Tianzhi Peng, Quan Wen, Gang Wang, Hao Jiang
Summary: Visible-light field effect phototransistors (FEPTs) with high detectivity and high speed are fabricated using a polarization induced photogate in a simple In0.15Ga0.85N/GaN heterostructure. Experimental results show that the polarization electric field can fully deplete the channel layer and leads to an ultra-low dark current, and the channel conductivity can be significantly promoted with visible-light illumination. Therefore, the FEPT achieves a high visible-light gain and a superhigh shot noise limited specific detectivity, as well as a high speed with rise/fall time of 15 ns/160 ns. These results not only present huge potential in visible-light photodetection, but also provide an insight into the application of polarization effects in wide bandgap semiconductors.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Feng Xie, Yufei Yao, Yan Gu, Zhijia Hu, Benli Yu, Guofeng Yang
Summary: A high-performance InGaN/GaN multiple quantum well p-i-n photodetector with patterned sapphire substrates was fabricated. The detector showed a low dark current density of <2.0 x 10(-10) A/cm(2) at -2 V bias voltage, with a high contrast ratio of photocurrent to dark current over 10(6). Furthermore, the peak responsivity reached 0.18 A/W at -10 V for a wavelength of 395 nm, corresponding to a maximum quantum efficiency of approximately 56%. In addition, the noise equivalent power (NEP) and normalized detectivity were 1.14 x 10(-11) W and 2.77 x 10(11) cm center dot Hz(0.5) center dot W-1, respectively. The high-performance of the photodetector is believed to be due to the high crystalline quality of the InGaN epilayer.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Physics, Condensed Matter
Koji Okuno, Koichi Mizutani, Kazuyoshi Iida, Masaki Ohya, Naoki Sone, Weifang Lu, Renji Okuda, Yoshiya Miyamoto, Kazuma Ito, Satoshi Kamiyama, Tetsuya Takeuchi, Motoaki Iwaya, Isamu Akasaki
Summary: In this study, the growth mechanism and defect structure of GaN-based nanowire multiple-quantum-shells (NW-MQSs) with cap layers combining tunnel junctions and n-GaN are investigated in detail. Three regions where defect structures are formed are identified and the defects are found to be mainly caused by low quality of the active layer, silicon nitride formed on the NW surface, and coalesced region of the cap layers in adjacent MQSs. The number of defects reaching the cap layer surface depends on the number of defects generated from the active layer.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Article
Chemistry, Physical
Ping-Feng Chi, Feng-Wu Lin, Ming-Lun Lee, Jinn-Kong Sheu
Summary: In this study, beta-Ga2O3/GaN-based solar-blind phototransistors were fabricated through a thermal oxidation process. The thermal-oxidized beta-Ga2O3 films exhibited a high-resistivity property and a (201)-orientated crystal phase. The HPTs showed a distinct cut-off wavelength and a bias-dependent responsivity.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Crystallography
Koji Okuno, Koichi Mizutani, Kazuyoshi Iida, Masaki Ohya, Naoki Sone, Weifang Lu, Renji Okuda, Yoshiya Miyamoto, Kazuma Ito, Satoshi Kamiyama, Tetsuya Takeuchi, Motoaki Iwaya, Isamu Akasaki
Summary: In this study, the growth mechanisms of n-type gallium nitride (GaN) cap layers for embedding nanowire-based multi-quantum-shell (NW-MQS) with a tunnel junction were investigated using the metal-organic vapor-phase epitaxy method. By controlling the growth pressures and temperatures at three stages, the cap layers were grown with different modes, resulting in cap layers with a flat surface for efficient optical device application.
JOURNAL OF CRYSTAL GROWTH
(2022)
Article
Physics, Applied
T. Liu, H. Watanabe, S. Nitta, J. Wang, G. Yu, Y. Ando, Y. Honda, H. Amano, A. Tanaka, Y. Koide
Summary: The leakage current caused by Si pileup at the regrowth interface of AlGaN/GaN HEMTs is significantly suppressed by the semi-insulating Mg-doped GaN layer. Treatment of the GaN template with HCl and H2O2/KOH solution before regrowth promotes the adsorption of Mg on the GaN surface, resulting in a highly resistive Mg-doped GaN channel layer. The p-n junction formed by the weakly p-type Mg-doped GaN layer and the n-type Si pileup layer depletes excess electrons at the regrowth interface, leading to a two orders of magnitude decrease in off-state drain leakage current of the HEMT device at 40V.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Jishi Cui, Jianping Zhou, Hongdi Xiao
Summary: InGaN-based multiple quantum wells embedded in nanoporous GaN layers were fabricated using electrochemical etching to improve the photoluminescence (PL) strength of the InGaN/GaN stacking layers. Among the three etching methods tested, HNO3 etching resulted in the highest enhancement of the PL strength, which can be attributed to stress relaxation, light scattering and reflection, and resonant cavity-induced spontaneous emission. Annealing the nanopore walls in NH3 atmosphere further improved the light extraction efficiency of the multiple quantum wells.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Artur Lachowski, Ewa Grzanka, Szymon Grzanka, Robert Czernecki, Mikolaj Grabowski, Roman Hrytsak, Grzegorz Nowak, Mike Leszczynski, Julita Smalc-Koziorowska
Summary: The thermal instability of InxGa1-xN quantum wells (QWs) hinders the construction of efficient blue and green LEDs and laser diodes. In this study, a method to overcome this problem by heavy Si doping of the GaN barrier layers is presented. The presence of silicon atoms increases the energy barrier for gallium vacancies migration, effectively reducing the possibility of diffusion of gallium vacancies. As a result, improved thermal stability of QWs was achieved and significant degradation was not observed up to temperatures of 980 degrees C.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Electrical & Electronic
Pradip Dalapati, Abdulaziz Almalki, Sultan Alhassan, Saud Alotaibi, Maryam Al Huwayz, Taiki Nakabayashi, Takashi Egawa, Makoto Miyoshi, Mohamed Henini
Summary: This study investigates the degradation mechanisms of InGaN/GaN multiple quantum well ultraviolet photodetectors (UV-PDs) by utilizing various optical and electrical measurements. The results indicate that the degradation of UV-PDs is primarily caused by newly generated defects.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Engineering, Electrical & Electronic
Lin Shang, Bingshe Xu, Shufang Ma, Huican Ouyang, Hengsheng Shan, Xiaodong Hao, Bin Han
Summary: By growing a p-In0.06Ga0.94N cap layer, the light output power of LEDs can be enhanced and the operating voltage can be decreased. Improvements in light extraction efficiency and lower contact resistence contribute to these enhancements.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Article
Optics
Jixing Chai, Liang Chen, Ben Cao, Deqi Kong, Sheng Chen, Tingjun Lin, Wenliang Wang, Yong Liu, Guoqiang Li
Summary: The PDs based on Gr/InGaN heterojunctions exhibit high responsivity and fast response, making them promising for selective detection in visible light communication systems.
Article
Multidisciplinary Sciences
Mikolaj Grabowski, Ewa Grzanka, Szymon Grzanka, Artur Lachowski, Julita Smalc-Koziorowska, Robert Czernecki, Roman Hrytsak, Joanna Moneta, Grzegorz Gawlik, Andrzej Turos, Mike Leszczynski
Summary: This experiment provides experimental evidence that point defects, most likely gallium vacancies, induce decomposition of InGaN quantum wells at high temperatures. The study found that point defects play an important role in the decomposition of InGaN at high temperatures by comparing samples grown on unimplanted and implanted GaN substrates.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
Wen-Jie Wang, Ming-Le Liao, Jun Yuan, Si-Yuan Luo, Feng Huang
Summary: The effects of GaN/InGaN asymmetric lower waveguide (LWG) layers on the photoelectrical properties of InGaN multiple quantum well laser diodes (LDs) were investigated theoretically. The optimal thickness and indium content of the InGaN insertion layer (InGaN-IL) in the lower waveguide were found to be 300 nm and 4% respectively. The thickness of the InGaN-IL mainly affects the output power and optical field distribution, and the highest output power achieved was 1.25 times that of the reference structure.
Article
Materials Science, Multidisciplinary
Yuntao Zhao, Guanghui Li, Shuai Zhang, Feng Liang, Mei Zhou, Degang Zhao, Desheng Jiang
Summary: The study found that the thickness of LT-Cap layer influences the InGaN/GaN multiple quantum well structure and luminescence characteristics. LT-Cap layer can weaken InGaN decomposition, but increasing LT-Cap layer thickness leads to increased polarization effect and red shift. Different LT-Cap layers affect tail state distribution and carrier emission energy shift.
OPTICAL MATERIALS EXPRESS
(2021)
Article
Engineering, Electrical & Electronic
Philipp Doering, Matthias Sinnwell, Stefan Mueller, Heiko Czap, Rachid Driad, Peter Brueckner, Klaus Koehler, Lutz Kirste, Michael Mikulla, Ruediger Quay
Summary: This study presents a comprehensive investigation on the performance of AlGaN/GaN high-electron-mobility transistors (HEMTs) regrown on Mg-implanted layers. The results confirmed a sharp doping profile in the regrown AlGaN/GaN stacks, even at high temperatures above 1000°C during standard metal-organic chemical vapor deposition (MOCVD). Static and dynamic characterization showed no impact on threshold voltage, transconductance, or saturation current, even for low channel thicknesses as small as 150 nm. The leakage current revealed various mechanisms including variable-range hopping (VRH) and Pool-Frenkel emission (PFE), depending on the applied voltage and electric field. The feasibility of the demonstrated process for large-scale wafer fabrication and its potential in future device developments were also demonstrated.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)