Article
Chemistry, Physical
Yong Ha Choi, Kwang Hyeon Baik, Suhyun Kim, Jihyun Kim
Summary: The etching process of beta-Ga2O3 semiconductor using phosphoric acid as demonstrated in this study showed an anisotropic etch pit formation along the [001] direction. The new exposed facet (-201) was found to be stable, and the optoelectronic performance was greatly improved through the effective removal of defects by PEC etching.
APPLIED SURFACE SCIENCE
(2021)
Article
Engineering, Electrical & Electronic
Abhishek Vaidya, Chinmoy Nath Saha, Uttam Singisetti
Summary: The letter presents the use of a modulation doping scheme to fabricate AlGaO/GaO heterostructure HFETs with significant improvements in peak transconductance, current, and power gain cutoff frequencies. The highly scaled transistors exhibit enhancement-mode operation and high electrical performance, with peak current gain cutoff frequencies reaching 30 and 37 GHz. However, the cutoff frequencies are limited by high source resistance at the regrowth interface, despite achieving a high f(T).L-G product of 4.8 GHz-mu m.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Chemistry, Physical
Qihao Zhang, Jiangwei Liu, Chunming Tu, Dongyuan Zhai, Min He, Jiwu Lu
Summary: High-performance beta-Ga2O3-based Schottky barrier diodes (SBDs) and metal-semiconductor field-effect transistors (MESFETs) were fabricated on a highly doped epitaxial wafer. The electrical properties and stabilities of these devices after annealing were investigated. The results showed excellent ON/OFF ratios for all SBDs, and the MESFETs exhibited pinch-off and saturation characteristics with high drain currents, surpassing previous reports. The study provides valuable insights for the development of practical applications of beta-Ga2O3-based electronic devices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Physics, Applied
Xinxin Yu, Hehe Gong, Jianjun Zhou, Zhenghao Shen, Fang-fang Ren, Dunjun Chen, Xin Ou, Yuechan Kong, Zhonghui Li, Tangsheng Chen, Shulin Gu, Rong Zhang, Youdou Zheng, Jiandong Ye
Summary: This Letter reports on the enhanced radio frequency (RF) performance in sub-micrometer scaled beta-Ga2O3 tri-gate FinFETs. The improved RF performance results from the enhanced gate control capability and the suppressed short-channel effects, suggesting that the tri-gate multi-fin architecture is a promising strategy to break the scaling limitation of the gate-channel aspect ratio toward high-performance beta-Ga2O3 RF MOSFETs.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Hitoshi Takane, Yuji Ando, Hidemasa Takahashi, Ryutaro Makisako, Hikaru Ikeda, Tetsuzo Ueda, Jun Suda, Katsuhisa Tanaka, Shizuo Fujita, Hidetaka Sugaya
Summary: Mist CVD was used to grow the ss-Ga2O3 channel layer on a semi-insulating ss-Ga(2)o(3) (010) substrate. The mobility and carrier concentration of the channel layer were 80 cm(2) V-1 s(-1) and 6.2 x 10(17) cm(-3), respectively. The device exhibited a pinch-off characteristic with a threshold gate voltage of -9 V, and showed promising performance for low-cost devices.
APPLIED PHYSICS EXPRESS
(2023)
Article
Materials Science, Multidisciplinary
Amir Abdi, Ali Naderi
Summary: An amended structure of metal-semiconductor field effect transistor (MESFET) in SOI technology, called TLO-SOI MESFET, is proposed. The use of oxide in the channel area improves the breakdown voltage and frequency characteristics of the device, and enhances other characteristics as well.
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Zimin Chen, Xing Lu, Yujia Tu, Weiqu Chen, Zhipeng Zhang, Shengliang Cheng, Shujian Chen, Hongtai Luo, Zhiyuan He, Yanli Pei, Gang Wang
Summary: The explosion of mobile data from the internet of things (IoT) is driving the development of 5G technology, which requires high-performance filters. This study explores the potential of epsilon-Ga2O3, a semiconductor with a higher piezoelectric constant than AlN, for use in piezoelectric devices. The results demonstrate the suitability of epsilon-Ga2O3 for application in 5G radio frequency (RF) front-ends.
Article
Materials Science, Multidisciplinary
Weiming Liu, Xudan Zhu, Junbo He, Yan Yang, Tiantian Huang, Xin Chen, Rongjun Zhang
Summary: This study demonstrates the tailored optical properties of Ti-doped/incorporating Ga2O3 thin films in the UV region through plasma-enhanced atomic layer deposition. The controlled Ti content in amorphous TGO thin films leads to bandgap tuning and redshifted absorption edges, as well as wide absorption for DUV photoelectronic responses in photodetectors.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Hardhyan Sheoran, Janesh K. Kaushik, Rajendra Singh
Summary: In this study, the temperature endurance capability of high-quality Pt-based Schottky Barrier Diodes (SBDs) fabricated on HVPE-grown & beta;-Ga2O3 was experimentally investigated. The SBDs showed outstanding thermal stability over repeated cycles of electrical measurements. A high Schottky barrier height (SBH) and near unity ideality factor were obtained at 300 K. The excellent thermal stability and endurance of the fabricated SBDs confirm their potential application in advanced power electronic devices.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Engineering, Electrical & Electronic
Daniel M. Dryden, Kyle J. Liddy, Ahmad E. Islam, Jeremiah C. Williams, Dennis E. Walker, Nolan S. Hendricks, Neil A. Moser, Andrea Arias-Purdue, Nicholas P. Sepelak, Kursti DeLello, Kelson D. Chabak, Andrew J. Green
Summary: We demonstrate a passivated MESFET fabricated on (010) Si-doped beta-Ga2O3 with breakdown over 2.4 kV without field plates, high Power Figure of Merit (PFOM), and high estimated Huang's Material Figure of Merit (HMFOM), owing to low gate charge and high breakdown. MESFETs with 13 μm source-drain spacing and 75 nm channel exhibited a current density of 61 mA/mm, peak transconductance of 27 mS/mm, and on-resistance of 133 Ω•mm. The device showed a PFOM competitive with state-of-the-art beta-Ga2O3 devices and a record high estimated HMFOM for a beta-Ga2O3 device, competitive with commercial wide-band gap devices. This demonstrates high-performance beta-Ga2O3 devices as viable multi-kV high-voltage power switches.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Ki-Tae Kim, Hye-Jin Jin, Wonjun Choi, Yeonsu Jeong, Hyung Gon Shin, Yangjin Lee, Kwanpyo Kim, Seongil Im
Summary: The study presents bottom gate architecture beta-Ga2O3 MESFETs using transition metal dichalcogenide (TMD) NbS2 and TaS2. Due to the large work functions of these TMDs, the MESFETs demonstrate good performance, including minimum subthreshold swing and small threshold voltage.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Laura E. Ratcliff, Takayoshi Oshima, Felix Nippert, Benjamin M. Janzen, Elias Kluth, Rudiger Goldhahn, Martin Feneberg, Piero Mazzolini, Oliver Bierwagen, Charlotte Wouters, Musbah Nofal, Martin Albrecht, Jack E. N. Swallow, Leanne A. H. Jones, Pardeep K. Thakur, Tien-Lin Lee, Curran Kalha, Christoph Schlueter, Tim D. Veal, Joel B. Varley, Markus R. Wagner, Anna Regoutz
Summary: Ga2O3 and its polymorphs have great potential for electronic structure engineering. In this study, a robust atomistic model of gamma-Ga2O3 is developed using density functional theory and machine-learning approach, which is validated by experimental results. This work is of significant importance for understanding the electronic structure of complex, disordered oxides.
ADVANCED MATERIALS
(2022)
Article
Physics, Applied
Kentaro Kaneko, Yasuhisa Masuda, Shin-ichi Kan, Isao Takahashi, Yuji Kato, Takashi Shinohe, Shizuo Fujita
Summary: Ultra-wide bandgap p-type alpha-(Ir,Ga)(2)O-3 films were achieved through unintentional or Mg doping, showing potential for high-quality pn heterojunction formation with n-type alpha-Ga2O3 due to their similar crystal structures and good lattice matching. Initial testing of a pn junction diode composed of these materials demonstrated promising performance.
APPLIED PHYSICS LETTERS
(2021)
Article
Multidisciplinary Sciences
Jincheng Zhang, Pengfei Dong, Kui Dang, Yanni Zhang, Qinglong Yan, Hu Xiang, Jie Su, Zhihong Liu, Mengwei Si, Jiacheng Gao, Moufu Kong, Hong Zhou, Yue Hao
Summary: In this study, Ga2O3 heterojunction PN diodes are demonstrated to overcome the challenges of high breakdown voltage and low doping, achieving high power figure-of-merit and showing great potential for next-generation power electronics applications.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Ruijia Zhang, Min Li, Gai Wu, Lijie Li, Zhaofu Zhang, Kang Liang, Wei Shen
Summary: Fl-Ga2O3 is a promising material for next-generation power electronic and optoelectronic devices due to its exceptional properties. This study investigates the effects of strain engineering on the electronic properties of fl-Ga2O3, revealing that strain manipulation can induce a bandgap transition and changes in effective masses and electron mobility. These findings provide important insights for utilizing strain engineering as a powerful tool for modulating fl-Ga2O3's electronic properties.
RESULTS IN PHYSICS
(2023)
Article
Physics, Applied
Junao Cheng, Scott Poehler, Masihhur Laskar, Lu Ma, Santhakumar Kannappan, Siddharth Rajan, Yiying Wu, Wu Lu
Summary: This study investigates the carrier transport mechanisms in chemical vapor deposited few-layer MoS2 at different temperatures using a two-terminal device configuration. The results reveal a transition in transport behavior from resonant tunneling to hopping, and eventually to band transport as the temperature increases. These findings are significant for understanding the material properties of future 2D semiconductor devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Andrew J. Green, James Speck, Grace Xing, Peter Moens, Fredrik Allerstam, Krister Gumaelius, Thomas Neyer, Andrea Arias-Purdue, Vivek Mehrotra, Akito Kuramata, Kohei Sasaki, Shinya Watanabe, Kimiyoshi Koshi, John Blevins, Oliver Bierwagen, Sriram Krishnamoorthy, Kevin Leedy, Aaron R. Arehart, Adam T. Neal, Shin Mou, Steven A. Ringel, Avinash Kumar, Ankit Sharma, Krishnendu Ghosh, Uttam Singisetti, Wenshen Li, Kelson Chabak, Kyle Liddy, Ahmad Islam, Siddharth Rajan, Samuel Graham, Sukwon Choi, Zhe Cheng, Masataka Higashiwaki
Summary: Gallium Oxide has become a leading ultra-wide band gap semiconductor technology due to its favorable material properties. This roadmap presents the current state-of-the-art and future challenges in the field, aiming to enhance device performance and design efficient microelectronic systems.
Article
Physics, Applied
Sheikh Ifatur Rahman, Zane Jamal-Eddine, Agnes Maneesha Dominic Merwin Xavier, Robert Armitage, Siddharth Rajan
Summary: In this paper, p-down green emitting LEDs with low turn-on voltage enabled by efficient tunnel junctions were demonstrated. The reduction of electrostatic depletion barrier for electron and hole injection was achieved by the polarization field alignment in the (In,Ga)N/GaN interface with p-down orientation. A single (In,Ga)N/GaN heterostructure quantum well active region with a GaN homojunction tunnel junction showed very low forward operating voltage and excellent electroluminescence emission at high current densities.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Ashok Dheenan, Joe F. McGlone, Nidhin Kurian Kalarickal, Hsien-Lien Huang, Mark Brenner, Jinwoo Hwang, Steven A. Ringel, Siddharth Rajan
Summary: In this study, we have developed an in situ Mg doping technique in plasma-assisted molecular beam epitaxy for compensating Si dopants and eliminating parasitic leakage paths in beta-Ga2O3. The technique achieved both abrupt and uniform Mg doping profiles over a wide range of concentrations. Capacitance-voltage characteristics confirmed the compensating effect of Mg dopants. Mg delta-doping was also shown to effectively eliminate source leakage in beta-Ga2O3 metal-semiconductor field effect transistor structure.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Patrick Fay, Jeong-Sun Moon, Siddharth Rajan
Summary: Advanced concepts in polarization engineering of III-N transistor structures offer great potential for significant improvements in device performance in microwave to millimeter-wave applications. By going beyond conventional design concepts and improving the physical understanding of electron transport and electrostatics, enhancements in device linearity, maximum operating voltage, and power-added efficiency can be achieved.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Taeyoung Kim, Chandan Joishi, Pao-Chuan Shih, Tomas Palacios, Siddharth Rajan
Summary: This work presents a theoretical analysis of the impact of surface states on vacuum field emission currents in semiconductors. It is found that in wide and ultra-wide bandgap semiconductors, the surface Fermi level is pinned below the conduction band, resulting in surface depletion barriers comparable to or higher than the electron affinity. Therefore, field emission analysis needs to consider both the electron affinity and the depletion region near the semiconductor surface.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Sushovan Dhara, Nidhin Kurian Kalarickal, Ashok Dheenan, Siddharth Rajan, Chandan Joishi
Summary: This work demonstrates a deep mesa etch design for efficient edge field termination in beta-Ga2O3 Schottky barrier diodes (SBDs). The design enables parallel plate fields higher than 4.1 MV/cm with minimal impact on the device's ON characteristics. The study also analyzes the effect of BCl3/Cl-2-based dry etch on (100) and (010) etched vertical sidewalls, revealing remarkable anisotropy in depletion.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Hyun-Soo Lee, Mohammad Wahidur Rahman, Darpan Verma, Violet M. Poole, Roberto C. Myers, Matthew D. McCluskey, Siddharth Rajan
Summary: In this study, a method to achieve selectively patterned Mg-doped GaN layers using hydrogen drive-in through PECVD SiNx films is demonstrated. The method selectively deactivates activated Mg-doped GaN layers through low-temperature annealing and is optically verified through spatially resolved photoluminescence measurements.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2022)
Article
Physics, Applied
Nidhin Kurian Kalarickal, Ashok Dheenan, Joe. F. F. McGlone, Sushovan Dhara, Mark Brenner, Steven. A. A. Ringel, Siddharth Rajan
Summary: We presented the design and fabrication of beta-Ga2O3 self-aligned lateral MOSFETs with a heavily doped beta-Ga2O3 cap layer. The fabricated device achieved a record high DC drain current density of 560 mA/mm at 5V drain bias, although the current density was limited by excessive self-heating. However, pulsed I-V measurements showed a record high current density of 895 mA/mm and a high transconductance of 43 mS/mm, indicating reduced self-heating in the device. These findings are promising for the development of high power density devices based on beta-Ga2O3.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Agnes Maneesha Dominic Merwin Xavier, Arnob Ghosh, Sheikh Ifatur Rahman, Andrew Allerman, Shamsul Arafin, Siddharth Rajan
Summary: Ultra-violet light emitting diodes emitting at 339 nm with transparent interband tunnel junctions were achieved using plasma-assisted molecular beam epitaxy. By utilizing compositionally graded n and p-type layers, a low voltage drop at the tunnel junction was obtained, leading to enhanced hole density and tunneling rates. The transparent tunnel junction-based UV LED exhibited a voltage drop of 5.55 V at 20 A/cm(2) and an on-wafer external quantum efficiency of 1.02% at 80 A/cm(2).
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Taeyoung Kim, Chandan Joishi, Zhanbo Xia, Nidhin Kurian Kalarickal, Camelia Selcu, Tyson Back, Jonathan Ludwick, Siddharth Rajan
Summary: In this paper, the field emission characteristics of beta-Ga2O3 nano-pillar arrays fabricated using a damage-free etching technique are demonstrated. The technique utilizes Ga flux in an ultra-high vacuum environment to form high aspect ratio Ga2O3 nano-pillars with atomic-scale etching precision. Electrically conductive Ga2O3 nano-pillars with uniform widths of 200-300 nm were realized without e-beam lithography. Furthermore, the field emission characteristics of the nano-pillars were modeled and validated with a field emission orthodoxy test.
Article
Nanoscience & Nanotechnology
Kartikey Thakar, Bipin Rajendran, Saurabh Lodha
Summary: This study presents an ultra-low power spiking neuron based on two-dimensional materials, which can accurately, timely and selectively detect moving obstacles. The neuron circuit exhibits high energy efficiency and biomimetic behavior, enabling the detection of obstacles at low energy cost while generating complex neuronal behaviors similar to biological systems.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Proceedings Paper
Computer Science, Hardware & Architecture
Mohammad Wahidur Rahman, Chandan Joishi, Nidhin Kurian Kalarickal, Hyunsoo Lee, Siddharth Rajan
Summary: In this study, a high permittivity dielectric (BaTiO3) integrated field-plate overlap design was introduced to efficiently manage the field of hybrid AlGaN/GaN lateral Schottky barrier diodes for achieving superior breakdown performance at low turn-on voltages. By incorporating high-permittivity dielectrics, the devices demonstrated high breakdown fields and high-power figures of merit, indicating the potential of realizing highly efficient kV class rectifiers.
2022 IEEE 34TH INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES AND ICS (ISPSD)
(2022)
