Boule Growth of Gallium Nitride

The group III-nitride semiconductors of Al, Ga, and In are current very promising candidates for use in the development of short wavelength visible and UV optoelectronic devices as well as use for high temperature, high speed, and/or high power semiconductor devices. specific device applications which are of interest include blue and UV LEDs and diode laser, solar blind UV detectors, and high power microwave devices. Indeed, the promise of the nitrides for these and other applications has been demonstrated, and significant improvements in nitride device development has been achieved. However, current nitride based device structures utilize heteroepitaxy, wherein a non-nitride material such as sapphire or SiC is used as a substrate. the use of lattice and/or structurally mismatched substrates limits the crystalline quality and, ultimately, the operational characteristics of nitride based devices. As is the case for the Si and group[ III-As materials, full utilization of a semiconductors properties cannot be realized until a suitable substrate is available which allows for growth of high quality homoepitaxial layers. This requires development of processes for growth of the substrate material as well as development of suitable post growth processing techniques such as sawing and polishing of the material. the purpose of the proposed Phase I program is to demonstrate the feasibility of a new approach for growth of large GaN bulk crystals suitable for processing into wafer material. We believe that by the end of Phase II part of the program growth of 25 mm diameter, 25 mm long GaN ingots will be demonstrated. we anticipate that the process will ultimately achieve growth of 50-75mm diameter GaN boules at a cost approximately the same as for GaAs.