This invention was made in part with support from the National Science Foundation Grant Number DMR 9315914.
The present invention relates to a process for forming high quality crystalline refractory materials, particularly gallium (Ill) nitride (GaN), from solid precursors. GaN is a material newly available for use in the optoelectronics industry fur the fabrication of light-emitting diodes (LEDs) and blue lasers. It is also possible that doped GaN crystals may have utility as semiconductors. A particularly suitable application is the replacement of standard light bulbs in large outdoor displays, traffic lights and street lighting by GaN LEDs. GaN crystals, when properly activated, fluoresce producing a bright blue glow which is about 60 times brighter than the best GaP based yellow-green LEDs and many times brighter than a standard light bulb which it would replace. Further, a GaN LED display would have an operating life far in excess of the standard light bulb.
Currently, bulk quantities of high purity, polycrystalline gallium nitride are not available. Current techniques to produce such materials require maintaining reactants at high temperatures and pressures for long periods of time. Prior attempts to manufacture GaN by reacting gallium iodide with lithium nitride, which appears to be a suitable approach, produces elemental Ga, nitrogen and Lil and not GaN. Thus there is a need for a low cost, rapid process to produce large quantities of powdered crystalline materials for use in such applications as lighting, signal displays, and flat screen displays for computers and television screens.