Effects of substrate pretreatment and annealing processes on AlN thin films prepared by EVPE

Herein, a novel process of substrate pretreatment and high temperature annealing for elementary source vapor phase epitaxy (EVPE) is shown to be capable of optimizing the surface flatness of the AlN single crystal thin film, thus increasing its suitability for application in deep ultraviolet optoelectronic devices. Specifically, the increased surface smoothness/flatness of the so-prepared AlN samples are confirmed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). In addition, the crystal quality, stress conditions and luminescence performance are significantly improved.