High Quality Al-Polar AIN Growth on (0001) Sapphire Using Polarity-Selective Thermal Etching by High Temperature Metalorganic Chemical Vapor Deposition.

ABSTRACT

In this study, we suggest a polarity-selective in-situ thermal etching and re-growth process for the fabrication of high quality Al terminated AIN epilayers by high temperature metalorganic chemical vapor deposition. Mixed-polar AIN layers grown on a thin (5 nm) buffer layer at a high temperature (950 degrees C) exhibited high crystalline quality. Surface morphologies of in-situ thermally etched AIN layers depended on the grain size and distance between grains. Increasing the initial grain size and diminishing the space between grains increased etching depth and width. During re-growth, threading dislocations were bent and annihilated in the vicinity of voids, which were formed by lateral growth of Al-polar AIN regions after thermal etching. Finally, a high quality Al-polar AIN template, as verified by an aqueous KOH solution, was successfully fabricated.