Growth of Bulk Single Crystal A1N Substrates for A1GaN Epitaxy

We propose a six month Phase I program to demonstrate the feasibility of growing A1N single crystals to serve as substrates for subsequent A1xGa1xN epitaxy. Our approach is to use a low pressure, high temperature (>>2000oC) furnace with a temperature gradient between the A1N charge and the deposition (seed) regions. Our approach is based on several innovations. These include the use of single precursor synthesized A1N powders that we feel will avoid carbon and oxygen contamination. Our reactor design is unique and has the flexibility of moving the charge or the seed to the high or the low temperature zones. This flexibility is based on one of our proprietary furnace designs. The crystallization approach we propose is a modified Bridgeman technique. The seeding initiates on the tip of a conical zone. in our future Phase II program, with the availability of flat single crystal substrates this design will be modified. Dr. Glen Slack currently at G.E. research and development Center will serve as a consultant on the project. He has the distinction of producing the only known bulk A1N single crystal using A1N powder. We feel that his association coupled with our unique A1N powder chemistry and the furnace design will enable us in demonstrating the feasibility of our approach in the Phase I program. Anticipated Benefits: High quality short wavelength lasers and UV detectors will result from a homoepitaxial scheme of A1N and A1GaN deposition on A1N substrates. These devices will find use in imaging, graphics, and multicolor video displays. They will also be useful for optical recording and storage, flame detection for boiler systems.