Mechanism of GaN quantum dots capped with AlN: An AFM, electron microscopy, and x-ray anomalous diffraction study

Abstract

Capping of GaN quantum dots with AlN has been studied at the monolayer scale by combining atomic force microscopy, high resolution electron microscopy, and grazing incidence x-ray anomalous diffraction. Consistent with the results provided by these three techniques, it has been demonstrated that, following a wetting of the dots by an AlN layer up to 4 ML coverage, subsequent capping is dominated by a preferential AlN growth in between the dots, eventually resulting in a complete smoothing of AlN. Interdiffusion has been shown to be negligible during this process, which makes the GaN/AlN system unique among semiconductors.