Article
Physics, Applied
Avinash Kumar, Uttam Singisetti
Summary: beta-Gallium oxide is a widebandgap semiconductor with potential applications in power electronics and radio frequency switching. This study investigates the high field electron transport in 2DEG and analyzes the factors affecting velocity saturation.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Dawei Wang, Dinusha Herath Mudiyanselage, Houqiang Fu
Summary: This work systematically explores the design space for delta-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 high electronmobility transistors (HEMTs) using TCAD simulation, investigating the effects of different delta-doping concentrations, positions, and widths on device performance. High delta-doping concentrations can improve transconductance and channel mobility but may degrade other performance indicators such as breakdown voltages (BVs).
IEEE TRANSACTIONS ON ELECTRON DEVICES
(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, Multidisciplinary
Zhan-Hui Zhou, Li Qun, Xiao-Min He
Summary: β-Ga2O3 has attracted much attention in the field of power and radio frequency electronics due to its ultrawide bandgap energy of about 4.9 eV and high breakdown field strength of about 8 MV/cm. The in-plane lattice mismatch between β-Ga2O3 and wurtzite AlN allows for the formation of an AlN/β-Ga2O3 heterostructure, which is a potential candidate for β-Ga2O3-based high electron mobility transistors (HEMTs).
ACTA PHYSICA SINICA
(2023)
Article
Crystallography
Sihua Ha, Jun Zhu
Summary: The binding energy of an off-center hydrogen-like impurity in an ultra-wide band gap β-Ga2O3/(AlxGa1 x)(2)O-3 core/shell nanostructure is studied. The influence of structural dimension, Al composition, and quantum confinement on the impurity states and binding energy is investigated. The results provide theoretical insights for the development of optoelectronic devices using β-Ga2O3 low-dimensional material systems.
Article
Engineering, Electrical & Electronic
Ashvinee Deo Meshram, Anumita Sengupta, Tarun K. K. Bhattacharyya, Gourab Dutta
Summary: A novel beta-(AlxGa1-x)(2)O-3/gallium oxide (Ga2O3) modulation-doped field-effect transistor (MODFET) with p-GaN gate is proposed and investigated for the first time. The performance and device operation of the proposed MODFET are evaluated using a TCAD device simulator calibrated with experimental results. The proposed MODFET exhibits higher driving capability and lower ON-resistance compared to conventional Ga2O3-MODFETs of similar device dimensions. The impact of individual device parameters on the electrical characteristics of the proposed device is also studied in detail. Additionally, an analytical model is developed to accurately estimate the threshold voltage of these normally-OFF devices, and it is rigorously validated across a wide range of device parameters.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Chemistry, Multidisciplinary
Basant Chitara, Edgar Dimitrov, Mingzu Liu, Tank R. Seling, Bhargava S. C. Kolli, Da Zhou, Zhuohang Yu, Amit K. Shringi, Mauricio Terrones, Fei Yan
Summary: The development of two-dimensional (2D) type-II heterostructures has revolutionized the field of photovoltaics, allowing for the capture of a broader spectrum of solar energy. This study investigates the potential of V-doped WS2 in combination with Bi2O2Se for high-performance photovoltaic devices. Various techniques confirm the superior charge transfer in V-WS2/Bi2O2Se heterostructures compared to pristine WS2/Bi2O2Se. The findings suggest that incorporating V-doped WS2 can tune charge transfer and provide a novel light-harvesting technique for the development of next-generation photovoltaic devices.
Article
Physics, Applied
Sushrut Modak, Leonid Chernyak, Alfons Schulte, Minghan Xian, Fan Ren, Stephen J. Pearton, Igor Lubomirsky, Arie Ruzin, Sergey S. Kosolobov, Vladimir P. Drachev
Summary: In experiments, minority hole diffusion length and lifetime were measured independently in Si-doped beta-Ga2O3 Schottky rectifiers irradiated with 18MeV alpha particles and 10MeV protons. Both parameters showed a decrease with increasing temperature. The non-equilibrium minority hole mobility was calculated from the measured diffusion length and lifetime, indicating that hole self-trapping is likely not significant in the 77-295K temperature range.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Jiaye Zhang, Joe Willis, Zhenni Yang, Ziqian Sheng, Lai-Sen Wang, Tien-Lin Lee, Lang Chen, David O. Scanlon, Kelvin H. L. Zhang
Summary: Ga2O3 is a promising wide band-gap semiconductor for high-power electronics and deep ultraviolet optoelectronics. This study investigated the effect of carrier concentration on the electronic structure of Si-doped Ga2O3 films using both experimental and theoretical approaches. It was found that heavily doped Ga2O3 exhibits band-gap renormalization and Si is a superior dopant that maintains high mobility.
Article
Materials Science, Coatings & Films
Michael A. Mastro, Marko J. Tadjer, Jihyun Kim, Fan Ren, Stephen J. Pearton
Summary: The design of beta-Ga2O3-based modulation-doped field effect transistors focuses on the role of self-heating and the resulting modification of the electron mobility profile. It is found that a decrease in drain current is attributed to position-dependent mobility reduction. Additionally, an undesired secondary channel can form at the modulation-doped layer.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Nanoscience & Nanotechnology
A. F. M. Anhar Uddin Bhuiyan, Lingyu Meng, Hsien-Lien Huang, Jith Sarker, Chris Chae, Baishakhi Mazumder, Jinwoo Hwang, Hongping Zhao
Summary: Phase pure beta-(AlxGa(1-x))(2)O-3 thin films were successfully grown on (001) oriented beta-Ga2O3 substrates using metalorganic chemical vapor deposition. The epitaxial growth of coherently strained beta-(AlxGa(1-x))(2)O-3 films with up to 25% Al compositions was achieved, as confirmed by high resolution x-ray diffraction. The presence of alloy inhomogeneity and local segregation of Al along the (201) plane was observed from atomic resolution STEM imaging, resulting in wavy and inhomogeneous interfaces in the beta-(AlxGa(1-x))(2)O-3/beta-Ga2O3 superlattice structure.
Article
Materials Science, Multidisciplinary
Jie Zhang, Jong Mok Ok, Yun-Yi Pai, Jason Lapano, Elizabeth Skoropata, Alessandro R. Mazza, Haoxiang Li, Amanda Huon, Sangmoon Yoon, Benjamin Lawrie, Matthew Brahlek, T. Zac Ward, Gyula Eres, H. Miao, Ho Nyung Lee
Summary: This paper presents the observation of an extremely large linear magnetoresistance (LMR) in SrNbO3/SrTiO3 heterostructures over a large carrier density range, with a high magnetoresistance of up to 150,000% at a carrier density far from the quantum limit regime. The study provides compelling evidence of a mobility-driven LMR in coherent electronic systems and sheds light on the proper categorization of transport properties in topological and correlated materials.
Article
Multidisciplinary Sciences
Mingze He, Joseph R. Matson, Mingyu Yu, Angela Cleri, Sai S. Sunku, Eli Janzen, Stefan Mastel, Thomas G. Folland, James H. Edgar, D. N. Basov, Jon-Paul Maria, Stephanie Law, Joshua D. Caldwell
Summary: Doped semiconductor substrates, such as InAs and CdO, enable significant tuning and dynamic modulation of hyperbolic phonon polaritons (HPhPs). By altering the photo-injected carriers in the substrate, HPhPs can be tuned with a maximum difference of 8.3 times. This study presents an important advancement in manipulating HPhPs.
NATURE COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Celesta S. Chang, Nicholas Tanen, Vladimir Protasenko, Thaddeus J. Asel, Shin Mou, Huili Grace Xing, Debdeep Jena, David A. Muller
Summary: The study reveals that the thermodynamically unstable gamma-phase exists in both doped beta-Ga2O3 films and beta-(AlxGa1-x)(2)O-3 films, with its thickness correlated to the growth temperature. In doped films, a surface layer of the gamma-phase is observed, and heating results in the growth of a gamma-phase region accompanied by the movement of surface Ga interstitials.
Article
Physics, Applied
Xiao-Fei Liu, Nikolai Spitzer, Haruki Kiyama, Arne Ludwig, Andreas D. Wieck, Akira Oiwa
Summary: This study investigates the magnetotransport property of GaAs/(Al,Ga)As heterostructure with short-period superlattice (SPSL) doping. After illumination at low temperature for a long time, the electron concentration inside the quantum well (QW) changes only by 5.9%. The quantum lifetime of the electron exhibits an anomalous behavior, increasing slightly and then decaying exponentially until saturation. The increase originates from the enhanced screening effect due to larger donor filling-fraction, while the decrease may be caused by scattering of ionized d+ states evolved from DX centers and transfer of excess electrons between the AlAs layers. This work provides insights into the mechanism of DX centers on the quantum transport properties of SPSL-doped heterostructures.
PHYSICAL REVIEW APPLIED
(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
Chemistry, Physical
Yu Pan, Congcong Le, Bin He, Sarah J. Watzman, Mengyu Yao, Johannes Gooth, Joseph P. Heremans, Yan Sun, Claudia Felser
Summary: YbMnBi2, a canted antiferromagnet, demonstrates a large anomalous Nernst effect (ANE) conductivity, making it a promising candidate for thermoelectric energy conversion applications. Its unique structure guarantees a large ANE and significantly lower magnetization compared to general ferromagnets.
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
Michael R. Scudder, Karl G. Koster, Joseph P. Heremans, Joshua E. Goldberger
Summary: Transverse thermoelectric generators have the potential to overcome limitations in commercial application of classical thermoelectric generators. Optimizing device design and controlling geometry is crucial for efficient waste heat recovery.
APPLIED PHYSICS REVIEWS
(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
Nanoscience & Nanotechnology
Keisuke Hirata, Kentaro Kuga, Masaharu Matsunami, Minyue Zhu, Joseph P. P. Heremans, Tsunehiro Takeuchi
Summary: This study reports a large magneto-thermal conductivity effect in Ag2Te, which can be used in heat flow switches and thermoelectric devices at various temperatures, including room temperature. When a magnetic field of mu H-0 = 9 T is applied perpendicular to the heat and electric currents, the thermal conductivity of Ag2Te decreases by 61%. This effect is mainly due to the suppressed electronic thermal conductivity and magnetoresistance effect, resulting in a significant increase in the thermoelectric figure of merit.
Article
Multidisciplinary Sciences
Brandi L. Wooten, Ryo Iguchi, Ping Tang, Joon Sang Kang, Ken-ichi Uchida, Gerrit E. W. Bauer, Joseph P. Heremans
Summary: This article experimentally demonstrates that an external electric field has an impact on the velocity of longitudinal acoustic phonons, thermal conductivity, and diffusivity in a bulk lead zirconium titanate-based ferroelectric. The changes observed are due to alterations in the phonon dispersion, not phonon scattering. This finding provides insights into the nature of thermal fluctuations in ferroelectrics and opens up possibilities for phonon-based all-solid-state heat switches, which are crucial for solid-state heat engines. A quantitative theoretical model combining piezoelectric strain and phonon anharmonicity explains the field dependence of these properties without any adjustable parameters, bridging the gap between thermodynamic equilibrium and transport properties. This effect is four times larger than previously reported effects attributed to field-dependent phonon scattering.
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
Chemistry, Multidisciplinary
Andrew M. Ochs, Gerhard H. Fecher, Bin He, Walter Schnelle, Claudia Felser, Joseph P. Heremans, Joshua E. Goldberger
Summary: KMgBi is a quantum material that exhibits axis-dependent conduction polarity and a greatly enhanced ordinary Nernst effect (ONE). It shows a significant zero-field transverse thermoelectric response and a new type of Nernst effect.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
J. V. Li, A. T. Neal, T. J. Asel, Y. Kim, S. Mou
Summary: We investigate the intermixing effects of doping profile and carrier emission from deep levels in the capacitance-voltage measurement of 8-Ga2O3 wide bandgap semiconductor material. We find that the non-uniformity of doping measured under practical conditions is mainly caused by artifacts due to carrier emission from deep levels. We develop a procedure to measure hysteresis in cyclic capacitance-voltage experiments for probing the deep levels contributing to the apparent doping profile. Analyzing this hysteresis enables more accurate determination of doping density and its spatial distribution, as well as extraction of energy, density, and capture cross-section of the deep levels.
Article
Physics, Applied
Joon Sang Kang, Dung Vu, Minyue Zhu, Joseph P. Heremans
Summary: The researchers optimized the band structure of Bi1-xSbx alloys to maximize the thermal chiral anomaly. They found that the chiral anomalies are maximized when the chemical potential is at the Weyl points and that Weyl fermions are protected against scattering on phonons and neutral defects. In their optimum material, around 30% of the total heat is carried by the anomalous heat current, which is highly switchable under a magnetic field.
PHYSICAL REVIEW APPLIED
(2023)
Article
Chemistry, Multidisciplinary
Ryan A. Nelson, Ziling Deng, Andrew M. Ochs, Karl G. Koster, Cullen T. Irvine, Joseph P. Heremans, Wolfgang Windl, Joshua E. Goldberger
Summary: Axis-dependent conduction polarity (ADCP) refers to the phenomena in which the charge polarity of carrier conduction can change from p-type to n-type depending on the direction of travel through the crystal. PdSe2, a semiconductor with 0.5 eV band gap, exhibits ADCP due to the complementary effective mass anisotropies in the valence and conduction bands. This unique electronic property of PdSe2 opens up potential applications in various technologies.
MATERIALS HORIZONS
(2023)
Article
Materials Science, Multidisciplinary
Dung D. Vu, Ryan A. Nelson, Brandi L. Wooten, Joseph Barker, Joshua E. Goldberger, Joseph P. Heremans
Summary: In magnetic materials with strong spin-lattice coupling, the sensitivity of the lattice thermal conductivity to an applied magnetic field can be changed by magnon-phonon interactions. This study demonstrates the control of lattice thermal conductivity by changing the magnetic phases of MnBi2Te4 through the application of a magnetic field. Different magnetic phases exhibit different responses of the lattice thermal conductivity to the magnetic field.
