Solvothermal growth of low-defect-density gallium nitride substrates

ABSTRACT: This Small Business Technology Transfer Phase I project will address the problem of obtaining low-defect-density gallium nitride single crystals for substrates to enable low-defect, high-performance epitaxial growth. Gallium nitride is a very promising material for numerous applications including surface acoustic wave devices, high-powered LEDs, UV diode lasers and high-powered RF devices to name just a few. Its use is limited however, because these applications require a high quality single crystal as a substrate for subsequent epitaxial thin film device engineering. Solvothermal growth, growing crystals in pressurized solvents well above their boiling points, is a simple extension of the natural process for the formation of gems. The ammonothermal technique shows promise for scale-up of GaN single crystals. Our approach exploits eight years of joint engineering and design of a proven, commercially operational technique between Advanced Photonic Crystals and Clemson University for hydrothermal growth of oxide crystals. To accomplish the objectives of Phase I the current hydrothermal model autoclave design will be adapted for ammonothermal crystal growth. The necessary ammonothermal transport chemistry will also be developed in this work. Kyma Technologies will supply seeds and feedstock for use in the ammonothermal growth. BENEFIT: The anticipated benefits from this contract will be commercially viable, large-scale production of bulk low-defect single crystals of gallium nitride for subsequent use as substrates in epitaxial device manufacturing. Devices for a number of applications including surface acoustic wave devices, high-powered LEDs, UV diode lasers and high-powered RF devices to name just a few.