Thermal stability of hydrogen in LiAlO2 and LiGaO2

Hydrogen as H-2 has been incorporated into LiAlO2 and LiGaO2 by both ion implantation and by exposure to a plasma at 250 degrees C. In the implanted samples, approximately 50% of the hydrogen is lost from the surface during annealing at 500 degrees C for 20 min, and essentially all is gone by 700 degrees C. This hydrogen retention is considerably less than for other materials that are being used as substrates for III-nitride epilayer growth, such as SiC and sapphire. The indiffusion of H-2 from a plasma is much faster for LiAlO2 with an apparent diffusivity at 250 degrees C of similar to 10(-13) cm(-2) s(-1), approximately two orders of magnitude larger than for LiGaO2. Hydrogen outdiffusion from LiAlO2 or LiGaO2 substrates during III-nitride epitaxy should not be a significant problem; the hydrogen should have left these materials at temperatures less than epitaxial layer growth temperatures. (C) 1996 American Institute of Physics.