Annealing of GaN under high pressure of nitrogen

Abstract

Gallium nitride, aluminum nitride and indium nitride are basic materials for blueoptoelectronic devices. The essential part of the technology of these devices isannealing at high temperatures. Thermodynamic properties of the Ga–N systemand their consequences to application of high nitrogen pressure for the annealingof GaN based materials are summarized.The diffusion of Zn, Mg and Au in high dislocation density heteroepitaxialGaN/Al2O3 layers will be compared with the diffusion in dislocation-free GaNsingle crystals and homoepitaxial layers. It will be shown that high dislocationdensity can drastically change the diffusion rates, which strongly affects theperformance of nitride devices.Inter-diffusion of Al, Ga and In in AlGaN/GaN and InGaN/GaN quantumwell (QW) structures will be also considered. It will be shown that incontrast to stability of metal contacts, which is strongly influenced bydislocations, the inter-diffusion of group III atoms in QW structures isnot affected strongly by the presence of high dislocation density. This isrelated to the different rate controlling slow process in these two diffusionprocesses. This feature of interdiffusion processes explains the success ofheteroepitaxial techniques in the technology of nitride based light emitting diodes.