Through the proposed research, we plan to demonstrate the feasibility of the ammonothermal growth method for commercial production of high quality GaN crystals. This will be achieved by fabrication of a classical autoclave especially designed for this process, demonstration of adequate solubility, and demonstration of transport and re-deposition of the material on GaN seeds. The ammonothermal crystal growth method is modeled after the very successful process of synthesizing a-quartz in supercritical water. Laboratory scale studies of GaN dissolution and transport in supercritical ammonia in presence of azides yielded comparable results to those in the quartz process. The availability of GaN crystals and wafers will enable epitaxial, lattice-matched growth of III-nitride device structures with orders of magnitude reduced dislocation densities in the active layers. Anticipated Benefits/Commercial Applications: The development of GaN substrate technology will directly lead to the fabrication of high power and high frequency electronic devices, and short wavelength optoelectronic devices. The development of a lattice-matched nitride substrate with low dislocation density will be beneficial to the entire nitride community and will ultimately lead to the fabrication of nitride-based, electronic and optoelectronic devices with improved device performance and lifetime. Since a variety of III-nitride device structures have been developed during the past ten years on less favorable substrates with large lattice mismatch, the penetration of high-quality GaN wafers into the market place can occur without delay and to the immediate benefit to device performance.
Keywords: electronic materials, GaN crystal growth, ammonothermal growth
