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
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
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
Xin Zhou, Ming Li, Jinzhong Zhang, Liyan Shang, Kai Jiang, Yawei Li, Liangqing Zhu, Zhigao Hu, Junhao Chu
Summary: In this study, Mg-doped beta-Ga2O3-delta films with (2) over bar 01 orientation were successfully grown on (0001)-sapphire substrates by pulsed laser deposition. The as-deposited films were proven to be p-type based on the transfer characteristic curves of a top-gate field effect transistor and rectification curves of the Mg-doped/undoped beta-Ga2O3-delta junction. Additionally, the Mg-doped beta-Ga2O3-delta films prepared at a specific oxygen partial pressure exhibited excellent optoelectrical performance, making them suitable for third-generation ultraviolet photodetectors.
IEEE ELECTRON DEVICE LETTERS
(2022)
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
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)
Review
Chemistry, Physical
Zeyu Chi, Jacob J. Asher, Michael R. Jennings, Ekaterine Chikoidze, Amador Perez-Tomas
Summary: This article discusses the importance of efficient electrical power management in achieving climate goals and introduces ultra-wide bandgap (UWBG) semiconductors as a promising technology for energy electronics. Gallium oxide-Ga2O3 and other oxide semiconductors are highlighted for their high-power and optoelectronic properties, which could revolutionize power electronics and contribute to a sustainable zero emission society.
Article
Engineering, Electrical & Electronic
Hongyu Liu, Yuangang Wang, Yuanjie Lv, Shida Han, Tingting Han, Shaobo Dun, Hongyu Guo, Aimin Bu, Zhihong Feng
Summary: High performance lateral beta-Ga2O3 metal-semiconductor field effect transistors (MESFETs) with ultra-high breakdown voltage (V-br) over 10 kV are demonstrated in this study. Planar isolation using B ion implantation is done to avoid damage and ragged mesa edge caused by traditional dry etching. T-shaped gate and source field plate (FP) are adopted to suppress peak electric field. The results show that the B ion implanted isolation and device structure used in this work improve the performance of lateral beta-Ga2O3 MESFETs.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Dangpo Wang, Xiaoli Lu, Xinkai Ding, Yue Zhao, Gaoyang Gou, Zekun Shi, Zhouning Zhang, Jianing Li, Zhezhe Cong, Xiaohua Ma, Yue Hao
Summary: Elastic strain engineering is an efficient tool to modify the physical properties of semiconductors. This study demonstrates the continuous application of elastic strain to beta-Ga2O3 material using a modified two-point bend method, and shows a significant reduction in the bandgap of beta-Ga2O3 under the bending state. The existence of strain gradient in the free-standing beta-Ga2O3 sheets under bending states is evidenced by confocal Raman spectroscopy. These findings provide experimental evidence of bandgap modification of beta-Ga2O3 by elastic strain and suggest a wider application of flexible Ga2O3 based devices.
MATERIALS TODAY PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Norah Alwadai, Zohoor Alharbi, Fatimah Alreshidi, Somak Mitra, Bin Xin, Hadeel Alamoudi, Kishor Upadhyaya, Mohamed N. Hedhili, Iman S. Roqan
Summary: In this work, a facile fabrication process for a high-responsivity solar-blind self-powered UV-C photodetector based on a p-n WBGS heterojunction structure is demonstrated. The heterojunction structures based on p-type MnO QDs and n-type Sn-doped beta-Ga2O3 microflakes show excellent solar-blind UV-C photoresponse characteristics. The XPS analysis confirms the good band alignment between p-type MnO QDs and n-type beta-Ga2O3 microflakes with a type-II heterojunction.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Physics, Applied
Adrian Chmielewski, Ziling Deng, Muad Saleh, Jani Jesenovec, Wolfgang Windl, Kelvin Lynn, John McCloy, Nasim Alem
Summary: The study investigates the atomic and electronic structure of a Hf-doped beta-gallium oxide crystal and finds that Hf dopants prefer octahedral sites and have little impact on the crystal structure. The bandgap values of Hf-doped beta-Ga2O3 are similar to those of unintentionally doped crystals, making Hf an excellent dopant candidate.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Jiahao Li, Yanda Ji, Rui Pan, Run Zhao, Ye Yuan, Weiwei Li, Hao Yang
Summary: Interfaces in heterostructures can be finely manipulated by epitaxy engineering, leading to tunable properties. Recent research has shown that heterostructures based on Ga2O3 can be used in high powered devices, and high density edge dislocations are observed at the interfaces. In addition to the dominant Schottky emission mechanism, Fowler-Nordheim tunneling is also revealed, which may be attributed to the edge dislocations at the interfaces.
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
Chemistry, Multidisciplinary
Anil Kumar Rajapitamahuni, Anusha Kamath Manjeshwar, Avinash Kumar, Animesh Datta, Praneeth Ranga, Laxman Raju Thoutam, Sriram Krishnamoorthy, Uttam Singisetti, Bharat Jalan
Summary: In this study, the highly reversible, electrostatic doping of beta-Ga2O3 films with tunable carrier densities using ion-gel-gated electric double-layer transistor configuration was reported. The plasmon-phonon coupling that dictates electron transport properties was investigated, and it was found that the room-temperature mobility initially increased and then decreased with increasing carrier density due to the plasmon-phonon coupling. The study also revealed the important antiscreening effect arising from dynamic screening of the electron-phonon interactions from the hybrid plasmon-phonon modes. Higher room-temperature mobility can be achieved by harnessing the dynamic screening of the electron-phonon interactions.
Article
Physics, Applied
Arkka Bhattacharyya, Shivam Sharma, Fikadu Alema, Praneeth Ranga, Saurav Roy, Carl Peterson, Geroge Seryogin, Andrei Osinsky, Uttam Singisetti, Sriram Krishnamoorthy
Summary: In this paper, beta-Ga2O3 metal-semiconductor field-effect transistors with superior reverse breakdown voltages and ON currents are realized. A special design and etching process are used to enhance its performance.
APPLIED PHYSICS EXPRESS
(2022)
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
Nanoscience & Nanotechnology
Yiwen Song, Arkka Bhattacharyya, Anwarul Karim, Daniel Shoemaker, Hsien-Lien Huang, Saurav Roy, Craig McGray, Jacob H. Leach, Jinwoo Hwang, Sriram Krishnamoorthy, Sukwon Choi
Summary: Ultra-wide band gap semiconductor devices based on fi-phase gallium oxide (Ga2O3) offer higher switching performance, efficiency, and lower manufacturing cost compared to current wide band gap power electronics. However, overheating remains the major challenge for the commercialization of Ga2O3 electronics, affecting device performance and reliability. By fabricating a Ga2O3/4H-SiC composite wafer and implementing a low-temperature epitaxy and device processing scheme, we achieved high thermal performance and a power figure of merit of 300 MW/cm2 in Ga2O3 devices, the highest reported thus far. Thermally optimized Ga2O3/diamond composite wafers with reduced Ga2O3 thickness and thinner bonding interlayers show potential for further reduction in device thermal impedance.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Engineering, Electrical & Electronic
Rujun Sun, Arkka Bhattacharyya, Muad Saleh, Sriram Krishnamoorthy, Michael A. A. Scarpulla
Summary: We studied defect properties of ALD-grown SiO2/beta-Ga2O3 MOS capacitors using C-V, UV-assisted C-V, and DLTS techniques. The defect properties were investigated on (100), (010), and (-201) orientations with and without remote O-2 plasma exposure before SiO2 deposition. Minor differences in types and total interface state densities were observed among these orientations. However, remote O-2 plasma exposure significantly increased the densities of initially empty fast charge states for all orientations. Mobile charges were detected at room temperature and 400 K, indicating surface damage caused by even remote O-2 plasma exposure.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Materials Science, Coatings & Films
Jacqueline Cooke, Praneeth Ranga, Arkka Bhattacharyya, Xueling Cheng, Yunshan Wang, Sriram Krishnamoorthy, Michael A. Scarpulla, Berardi Sensale-Rodriguez
Summary: We report the discovery of a new type of structural defect in beta-Ga2O3 homoepitaxial thin films, which we call sympetalous defects. These defects consist of a line defect in the substrate combined with a multi-faceted inverted polycrystalline pyramid in the epitaxial film. Photoluminescence microscopy revealed polarization-dependent luminescence and circular dichroism at these defects. Understanding and controlling these defects is important for modifying film properties, affecting device yields, and influencing characterization experiments.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
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
Physics, Applied
Saurav Roy, Arkka Bhattacharyya, Carl Peterson, Sriram Krishnamoorthy
Summary: We present a vertical beta-Ga2O3 Schottky barrier diode with a field plate oxide of BaTiO3, which exhibits a breakdown voltage of 2.1 kV. The high breakdown voltage is achieved by using a thick drift layer of 11 μm with a low effective doping concentration. The introduction of a high-k dielectric with a dielectric constant of 248 significantly improves the breakdown voltage without impacting the on-state performance. Analysis of the diode dimensions reveals a uniform distribution of breakdown voltages for the field-plated SBDs. Power losses in both on and off states are analyzed and compared to non-field-plated devices, and the switching losses are estimated analytically.
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Arkka Bhattacharyya, Carl Peterson, Takeki Itoh, Saurav Roy, Jacqueline Cooke, Steve Rebollo, Praneeth Ranga, Berardi Sensale-Rodriguez, Sriram Krishnamoorthy
Summary: We demonstrate a new substrate cleaning and buffer growth scheme in beta-Ga2O3 epitaxial thin films using MOVPE. By growing a low-temperature un-doped Ga2O3 buffer followed by a transition layer to high-temperature Si-doped Ga2O3 channel layers, continuous growth of the channel structure was achieved. The parasitic Si channel at the epilayer-substrate interface was effectively compensated through solvent cleaning and hydrofluoric acid treatment. This substrate cleaning combined with the LT buffer scheme shows the potential for designing Si-doped beta-Ga2O3 channels with exceptional transport properties.
Article
Physics, Applied
Esmat Farzana, Saurav Roy, Nolan S. Hendricks, Sriram Krishnamoorthy, James S. Speck
Summary: In this study, PtOx/thin Pt Schottky contacts combined with a high permittivity dielectric (ZrO2) field-plate were used for Schottky barrier engineering in high-voltage vertical beta-Ga2O3 diodes. The results showed that the PtOx/thin Pt/beta-Ga2O3 contact exhibited improved reverse blocking performance and lower turn-on voltage compared to plain metal Pt/beta-Ga2O3 Schottky diodes and plain oxidized metal PtOx/beta-Ga2O3 diodes. Furthermore, the implementation of a high permittivity dielectric field-plate assisted in edge-field management and enabled a higher breakdown voltage. These findings suggest that the PtOx/thin Pt/beta-Ga2O3 Schottky contact, combined with a high permittivity field-plate, has the potential for enabling high-performance and efficient vertical beta-Ga2O3 power switches.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Erdal Mutlu, Ajay Panyala, Nitin Gawande, Abhishek Bagusetty, Jeffrey Glabe, Jinsung Kim, Karol Kowalski, Nicholas P. Bauman, Bo Peng, Himadri Pathak, Jiri Brabec, Sriram Krishnamoorthy
Summary: This paper presents the TAMM framework for productive and scalable development of computational chemistry methods. By decoupling computation specifications from execution, TAMM allows domain scientists to focus on algorithmic requirements while optimizing performance on various computing systems. The modular structure of TAMM supports different hardware architectures and incorporates new algorithmic advances.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Computer Science, Theory & Methods
Ang Li, Samuel Stein, Sriram Krishnamoorthy, James Ang
Summary: This article proposes a low-level benchmark suite called QASMBench, which provides insightful evaluation metrics for NISQ devices, QC programming compilers, schedulers, assemblers, and quantum system simulators. It consolidates commonly used quantum routines and kernels from various domains and introduces four circuit metrics to analyze the execution efficiency and error susceptibility. QASMBench can be launched and tested on multiple NISQ platforms.
ACM TRANSACTIONS ON QUANTUM COMPUTING
(2023)
