Large Area Gallium Nitride Substrates

We propose to produce large bulk single crystals of gallium nitride by utilizing the rapid growth rates afforded by halide vapor phase epitaxy. Seed crystals will be grown by MOCKED on new lattice matched oxide substrates. The thin gallium nitride film will protect the oxide substrate from attack by HC1. Anticipated growth rates will be 50 to 100 microns per hour. Initial nitride films on sapphire grown at 72 microns/hour are excellent single crystals. The oxide substrates will subsequently be removed by wet chemical etching, leaving large area free standing wafers of gallium nitride. Such wafers will be made available commercially by NZ Applied Technologies for homoepitaxial growth of gallium nitride films by metal organic chemical vapor deposition. With a conducting substrate, present contacting problems will be eliminated. We shall prepare blue GaN light emitting diodes on our new wafers to demonstrate their utility. It is clear that only large bulk single crystals of gallium nitride can alleviate the electrical and optical problems that plague present gallium nitride thin films grown on unmatched sapphire substrates.