Heterogeneous Integration of Diamond and Ultrawide-Bandgap Semiconductors for Fundamental Phonon and Electron Transport Studies
Abstract
Innovative materials are investigated for achieving the integration of ultra-wide bandgap (UWBG) materials, diamond and Al(Ga)N with high Al content. Based on superior material properties, such as thermal conductivity, carrier mobility, and breakdown field, UWBG materials are promising for revolutionizing key DOD and civilian technologies. Areas of immediate and future DOD need include high-power and RF devices, deep-UV photonics, quantum information and extremeenvironment applications including robust high-temperature operation. To make advances toward developing these technologies, extensive materials research is needed to achieve high-quality heteroepitaxy, effective p- and n-type doping, and heat conduction for thermal management. Heat extraction from device architectures requires achieving high values of k and low interfacial thermal boundary resistance (TBR). These are the principal limiting factors in electronics. Each is challenging since k depends strongly on material properties and deposition methods, while TBR is heavily influenced by interfaces of heterostructures. In diamond, with its established superior thermal conductivity, complexities arise from growth conditions and seedingÑwhich influences polycrystal size and even orientationÑthat result in varied k values even within a given thin film. Bulk AlN also has a high k, although achieving the same in epitaxial layers requires excellent crystal quality, and the AlGaN alloys exhibit much lower k which may be improved by growth. Systematic studies will focus on growth of diamond using hot-filament chemical vapor deposition (CVD) and Al(Ga)N using metalorganic CVD (MOCVD). To achieve material integration, and understanding of the resulting properties, we identify four primary tasks: ¥ Selective Growth of Diamond on Al(Ga)N for Thermal Integration will focus on demonstrating selective diamond on UWBG materials and achieving improvements in the preferred polycrystalline diamond orientation and morphology. ¥ Growth of UWBG Semiconductor on 3D Engineered Diamond/Al(Ga)N Surfaces via epitaxial-lateral overgrowth (ELOG) of Al(Ga)N to achieve conditions for optimizing thermal characteristics as well as electrical performance across a p-diamond / n-Al(Ga)N junction. ¥ Physical, Electrical, Thermal and Optical Characterization emphasizing electron microscopy (scanningÐSEM and transmissionÐSTEM), design and test of electrothermal test structures to extract thermal conductivity (k) and thermal boundary resistance (TBR). ¥ Integration of Diamond and AlN / AlGaN for Demonstrating UWBG p-n Junctions based on a novel selective diamond / ELOG Al(Ga)N structure. We have exciting preliminary results based on prior and current research efforts. The results include selective deposition of diamond on Si and GaN substrates, three-dimensional (3D) integration of diamond and GaN via ELOG, electron microscopy, and micro-Raman imaging. The proposed work is distinct from our previously- and currently-funded research projects. Texas State University is a Hispanic serving institution with 48% racial minorities and 37% Hispanic enrollment, along with large enrollment of veterans and first-generation students. We rank 14th in the nation for the number of bachelorÕs degrees awarded to Hispanic students. Dr. Edwin Piner has extensive industrial and academic expertise in heteroepitaxy and materials research, device processing, and testing. Dr. Mark Holtz has extensive expertise in optical characterization and nanoscale heat transport. All facilities needed for this research are in place.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 20, 2020
- Source ID
- W911NF2010285
Entities
People
- Edwin Piner
Organizations
- Army Contracting Command
- Office of the Secretary of Defense
- Texas State University