Article
Engineering, Electrical & Electronic
Reetendra Singh, Anand Roy, C. N. R. Rao
Summary: Carbon-doped gallium nitride is a promising material for optoelectronic devices, and studying its defects can provide insights into possible transitions. Carbon-doped GaN was obtained through a simple solid-gas reaction. Spectroscopic analysis revealed the presence of an isolated C-N defect state and the formation of a C-N-O-N complex. In heavily doped samples, blue luminescence related to oxygen defects was quenched, and carbon-related yellow luminescence appeared.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Jinyuan Xu, Ailing Chen, Linfeng Yu, Donghai Wei, Qikun Tian, Huimin Wang, Zhenzhen Qin, Guangzhao Qin
Summary: In this paper, the stable structure of a monolayer CuI with ultra-low thermal conductivity and an ultra-wide direct bandgap is predicted from first-principles calculations. This material shows potential applications in transparent and wearable electronics.
Article
Optics
Ekaterina Dementeva, Kseniia N. Orekhova, Marina G. Mynbaeva, Maria Zamoryanskaya
Summary: This paper investigates the cathodoluminescent properties of point defects in bulk GaN samples grown by HVPE technique. The cathodoluminescence spectra of GaN show two broad luminescence bands in the blue and yellow ranges. Each luminescence band is associated with several point defects - luminescence centers with similar spectral positions but different decay times. The paper proposes a technique for estimating the relative content of luminescent centers based on measuring cathodoluminescence intensity dependence on electron beam current density and decay times. Changes in the relative contents of point defects - luminescence centers are determined for different regions of the sample, and the excitation capture efficiency is constant for luminescence centers emitting in the yellow range.
JOURNAL OF LUMINESCENCE
(2022)
Article
Engineering, Electrical & Electronic
Saurabh Kharwar, Sangeeta Singh, Neeraj K. Jaiswal
Summary: The study investigates the interaction between gallium nitride nanoribbon (GaNNR) and toxic heavy metals (HMs). Comparisons are made between the structural and electronic behavior of HM-interacted GaNNRs and bare GaNNRs, revealing significant changes. Lead (Pb)-ZGaNNR-Pb is found to be the most stable structure, followed by zinc (Zn)-ZGaNNR-Zn and mercury (Hg)-ZGaNNR-Hg. The conductivity of HM-interacted GaNNRs suggests their potential applications as nanoscaled sensors for toxic HM detection.
IEEE SENSORS JOURNAL
(2023)
Article
Physics, Multidisciplinary
Zheng-Zhao Lin, Ling Lu, Xue-Feng Zheng, Yan-Rong Cao, Pei-Pei Hu, Xin Fang, Xiao-Hua Ma
Summary: AlGaN/GaN high electron mobility transistors (HEMTs) exhibit significant changes in electrical characteristics after heavy ion irradiation, including threshold voltage shift and decrease in saturation currents. Irradiation induces defects and tunneling sites, increasing current collapse and the number of surface state traps.
Article
Engineering, Electrical & Electronic
Daniel M. Fleetwood, Andrew O'Hara, Theresa Stellwag Mayer, Michael R. Melloch, Sokrates T. Pantelides
Summary: The significant increase in thermal carrier generation rates in MBE-grown p-i-n-i-p GaAs structures is attributed to deactivation of hydrogen-defect/impurity complexes during high-intensity, low-energy electron-beam irradiation. Quantum calculations suggest that deactivation of oxygen impurities is likely the cause of this degradation, with electric-field and excess-carrier-induced dehydrogenation of O-As-H complexes identified as a likely rate-limiting process.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2021)
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
Malgorzata Sznajder, Roman Hrytsak
Summary: Integration of diamond with GaN-based high-electron-mobility transistors improves thermal management, influencing the reliability, performance, and lifetime of GaN-based devices. By conducting first principles calculations on the stability of diamond-GaN interfaces, researchers have identified stable adsorption sites for C atoms on Ga- and N-terminated surfaces, and demonstrated ways to improve the energetic stability of diamond-GaN interfaces through reconstructions induced by substitutional dopants.
Article
Materials Science, Multidisciplinary
D. S. Gomes, J. M. Pontes, S. Azevedo
Summary: This study investigates the structural stability and electronic properties of hydrogenated gallium nitride monolayers (GaN(H)) using density functional theory (DFT), and explores the modulation of these properties through defects and chemical doping. The M1-GaN(H) structure exhibits better formation energy and stability, acts as a semiconductor with a wide bandgap of 3.45 eV, and shows potential for electronic device applications.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Chemistry, Physical
Jerome A. Cuenca, Matthew D. Smith, Daniel E. Field, Fabien C-P Massabuau, Soumen Mandal, James Pomeroy, David J. Wallis, Rachel A. Oliver, Iain Thayne, Martin Kuball, Oliver A. Williams
Summary: The study investigates the thermal stresses induced by diamond directly deposited onto III-nitride (III-N) heterostructure membranes, using analytical methods, numerical models, and experimental validation. It is found that the thermal stresses are mainly caused by the mismatch in coefficient of thermal expansion (CTE), and can be reduced by pre-stressing the membrane.
Article
Engineering, Electrical & Electronic
S. Garcia-Sanchez, I. Iniguez-de-la-Torre, S. Perez, T. Gonzalez, J. Mateos
Summary: Monte Carlo simulations were used to optimize the epilayer structure of GaN planar Gunn diodes to achieve ultrahigh-frequency oscillations. Practical considerations were taken into account, such as limitations of the fabrication process and mitigation of self-heating effects. The best results were obtained with an active layer thickness of 150 nm and a doping of 5 x 10(18) cm(-3), providing 350 GHz Gunn oscillations with a contact separation of 0.5 μm.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Chemistry, Multidisciplinary
Yahya Mohtashami, Larry K. Heki, Matthew S. Wong, Jordan M. Smith, Jacob J. Ewing, William J. Mitchell, Shuji Nakamura, Steven P. DenBaars, Jon A. Schuller
Summary: Researchers demonstrate metasurface LEDs that emit directional or focused light, showing advanced phase control technology. These metasurface LEDs exhibit better external quantum efficiency than unpatterned LEDs, providing possibilities for the development of high-efficiency metal-free LED devices.
Article
Engineering, Electrical & Electronic
Sulagna Chatterjee, Moumita Mukherjee
Summary: This article reports the opto-electronic switching properties of a GaN/AlGaN lateral Avalanche Transit Time (ATT) diode oscillator. A novel technique is used to incorporate the 2DEG effect in the two-terminal device through the conduction band offset and application of Cathode Field Plate (CFP) combined with lateral orientation. The performance superiority of the proposed electrical and optical switches over conventional silicon devices is demonstrated. The newly designed ATT diode shows enhanced performance due to the high mobility 2DEG transport region formed by the GaN/AlGaN conduction band offset and the unique CFP and lateral orientation.
MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS
(2023)
Article
Engineering, Electrical & Electronic
Muhammad Saddique Akbar Khan, Hui Liao, Guo Yu, Imran Iqbal, Menglai Lei, Rui Lang, Zehan Mi, Huanqing Chen, Hua Zong, Xiaodong Hu
Summary: Two innovative techniques, serpentine channel pattern sapphire substrate (SCPSS) and InGaN interlayer (IL), are proposed to effectively reduce threading dislocations (TDs) in GaN-based devices. Experimental results demonstrate the effectiveness of these techniques in decreasing the number of TDs and improving material quality.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Engineering, Electrical & Electronic
Giovanni Alfieri, Yusuke Fujii, Ruggero Micheletto
Summary: Opto-electronic properties of semiconductors can be altered by impurities and their complexes with intrinsic point defects, such as vacancies. Helium is one such impurity that is incorporated into gallium nitride (GaN) for various technological purposes. However, its electrical activity in GaN and its impact on dopants are not known. In this study, a density functional theory was used to investigate the behavior of substitutional helium and its complexes in wurtzite GaN. It was found that helium is unstable at nitrogen sites and forms nitrogen vacancies, leading to the creation of donor states close to the valence band edge. On the other hand, the presence of a gallium vacancy leads to the formation of an energetically stable complex that generates acceptor states close to the conduction band edge. These findings provide insights into the behavior of helium in GaN and its potential implications for device isolation.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)