TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace
OBJECTIVE: Develop and demonstrate Beta-Gallium Oxide (ß-Ga2O3) epitaxial structures suitable for fabrication of Metal Oxide Semiconductor Field Effect Transistor (MOSFET) and High Electron Mobility Transistor (HEMT) devices.
DESCRIPTION: Next generation Air Force sensing systems depend on continued electronic materials innovation leading to enabling performance capabilities. Interest in ß-Ga2O3 has grown recently due to its unique combination of a large bandgap (4.8eV), estimated breakdown field (8 MV/cm), high electron mobility and availability of native single crystal substrates using inexpensive melt-based growth methods [1-5]. ß-Ga2O3 possesses a larger bandgap, higher breakdown voltage and lower on-resistance than those of Silicon Carbide (SiC) and Gallium Nitride (GaN). Exploitation of ß-Ga2O3 semiconductors holds promise for revolutionary improvements in the cost, size, weight and performance of a broad range of radio frequency, power switching and opto-electronic components utilized in radar, electronic warfare and communication systems.
The realization of devices with optimal performance will require controlled growth of doped, high quality, homo/hetero-epitaxial structures on ß-Ga2O3 substrates. Common approaches under consideration for homo/hetero-epitaxial film growth include Molecular Beam Epitaxy (MBE), Metal-Organic Chemical Vapor Deposition (MOCVD), Metal-Organic Vapor-Phase Epitaxy (MOVPE) and Halide Vapor-Phase Epitaxy (HVPE). Homo-epitaxial, doped ß-Ga2O3 films can be grown enabling fabrication of MOSFET devices. Growth of hetero-epitaxial structures such as (AlxGa1-x)2O3/ Ga2O3 or (InxGa1-x)2O3/ Ga2O3 support fabrication of HEMT devices [6]. There is a need for a viable US-based source to develop and scale ß-Ga2O3 epitaxial processes to underpin and help drive the development of next generation ultra-high performance devices.
PHASE I: Develop growth parameters for; (i) homo-epitaxial growth of MOSFET structure comprised of doped Ga2O3 films on bulk semi-insulating ß-Ga2O3 substrates and (ii) hetero-epitaxial growth of HEMT structure comprised of doped (AlxGa1-x)2O3/ Ga2O3 or (InxGa1-x)2O3/ Ga2O3 films on bulk (010) semi-insulating ß-Ga2O3 substrates. Deliver epitaxial wafers for Government evaluation.
PHASE II: Demonstrate; (i) homo-epitaxial growth of MOSFET structure comprised of doped Ga2O3 films on bulk (010) 50mm semi-insulating ß-Ga2O3 substrates and (ii) hetero-epitaxial growth of HEMT structure comprised of doped (AlxGa1-x)2O3/ Ga2O3 or (InxGa1-x)2O3/ Ga2O3 films on bulk (010) 50mm semi-insulating ß-Ga2O3 substrates with nm-scale thickness uniformity at sub-nm RMS roughness levels. Characterize the epitaxial properties and modify the structure accordingly to enhance device performance.
PHASE III: Phase III shall address the commercialization of the product developed as a prototype in Phase II. Commercialize device-quality homo/hetero-epitaxial layers to device partners.
REFERENCES: 1. M. Higashiwaki, K. Sasaki, A. Kuramata, T. Masui, and S. Yamakoshi, "Gallium oxide (Ga2O3) metal-semiconductor field-effect transistors on single-crystal beta-Ga2O3 (010) substrates," Applied Physics Letters, vol. 100, Jan 2 2012.2. M. Higashiwaki, K. Sasaki, T. Kamimura, M. H. Wong, D. Krishnamurthy, A. Kuramata, et al., "Depletion-mode Ga2O3 metal-oxide-semiconductor field-effect transistors on beta-Ga2O3 (010) substrates and temperature dependence of their device characteristics," Applied Physics Letters, vol. 103, Sep 16 2013.3. W. S. Hwang, A. Verma, H. Peelaers, V. Protasenko, S. Rouvimov, H. Xing, et al., "High-voltage field effect transistors with wide-bandgap beta-Ga2O3 nanomembranes," Applied Physics Letters, vol. 104, Jun 16 2014.4. K. Sasaki, A. Kuramata, T. Masui, E. G. Villora, K. Shimamura, and S. Yamakoshi, "Device-Quality beta-Ga2O3 Epitaxial Films Fabricated by Ozone Molecular Beam Epitaxy," Applied Physics Express, vol. 5, Mar 2012.5. K. Sasaki, M. Higashiwaki, A. Kuramata, T. Masui, and S. Yamakoshi, "Ga2O3 Schottky Barrier Diodes Fabricated by Using Single-Crystal beta-Ga2O3 (010) Substrates," Ieee Electron Device Letters, vol. 34, pp. 493-495, Apr 2013.6. R. Wakabayashi, K. Sasaki, A. Ohtomo, et al., ¬œGrowth and electric properties of conductive (AlxGa1-x)2O3 films, 1st International Workshop on Gallium Oxide and Related Materials, November 3-6, 2015.
KEYWORDS: Gallium Oxide, Epitaxy, Wide Bandgap Semiconductor
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