NICOP - Growth and characterization of homoepitaxial beta-Ga2O3 on native substrates for vertical power device application
Abstract
Growth and characterization of homoepitaxial beta-Ga2O3 on native substrates for vertical power device applicationa. Technical:The single-crystal monoclinic (beta) phase of Ga2O3 is an excellent candidate for high-power, high-temperature electronic device applications due to its wide bandgap (4.8 eV) and high breakdown field (8 MV/cm), yielding a nearly ten-fold higher Baliga figure of merit than that of 4H-SiC (BFOM/Ga2O3 = 3444, BFOM/4H-SiC = 300). In addition, the intrinsic carrier concentration of this material is extremely low (ni = 1.8e-22/cm3), enabling low generation/ recombination rates and thus low leakage currents. Consequently, gallium oxide has a potential of being a significantly better power electronic device then GaN and SiC. Nevertheless, the growth of a thick, low-doped Ga2O3 drift region has proven challenging with current reactor designs. Past literature on Ga2O3 epitaxy reports growth rates on the order of a hundred nm/hr, which reasonably excludes the growth of thick drift layers. Therefore, it is critical to achieve high growth rate while maintaining high epitaxial quality in realizing Ga2O3 power devices. Recently Tamura Corp. (Novel Crystal Technology is a subsidiary) demonstrated 5 micron/hour growth rate using Hydride Vapor Phase Epitaxy (HVPE) while achieving low doping concentration of less than 1e13/cm^3. Tamura also produces native 2-inch diameter beta-Ga2O3 substrates enable growth of lattice-matched low defect density epitaxial beta-Ga2O3. In this project, Novel Crystal Technology (NCT) will collaborate with NRL Code 6880 on developing Ga2O3 homoepitaxial films in excess of 30 microns for high voltage switches the while maintaining high-rate growth and precise doping control. NCT will interrogate the control of free electron and hole concentrations via epitaxial and implant doping and activation annealing. In addition, high quality epitaxial Ga2O3 will be passivated in situ by SiO2, HfO2, or Al2O3 (crystalline or amorphous) for a low-defect interface passivation and gate dielectric using molecular beam epitaxy. The ultimate goal is to demonstrate the feasibility of power Ga2O3 transistor operating at over 10 kV. The close collaboration and division of labor between NCT and NRL are shown clearly in the proposed tasks. b. Relevance: Given the wide bandgap, gallium oxide is an excellent candidate for high voltage switches in power electronics for future electric ships. It is also a good candidate for applications in harsh conditions such as high temperature sensors and solar-blind photodetectors. The research could have impact on the following Naval S&T Focus Areas: electromagnetic maneuver warfare, platform design & survivability, power and energy, and power projection & integrated defense. c. Coordination: Dr. Lynn Petersen of ONR Code 33, Dr. Fritz Kub and Dr. Marko Tadjer of NRL 6800. Although Dr. Petersen can t co-fund the NICOP in FY16, but will consider co-funding in the out-years. Drs. Petersen and Kub also have an STTR call on the gallium oxide topic (N16A-T023). d. Desired Outcome: The knowledge on Ga2O3 homoepitaxial film growth mechanisms and doping control is critical to the realization of Ga2O3-based high power switches. The synergetic collaboration between NRL and the top provider of Ga2O3 will enable NRL to stay at the forefront of Ga2O3 technology. From the research results, the Navy will be able to access the feasibility and practicality of Ga2O3 as a high power, high voltage switch material
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 23, 2016
- Source ID
- N629091612217
Entities
People
- Akito Kuramata
Organizations
- Novel Crystal Technology, Inc.
- Office of Naval Research
- United States Navy