Series resistance in n-GaN/AIN/n-Si heterojunction structure

A nominally nondoped GaN. was grown on an (III)Si substrate using an AIN intermediate layer and the electrical resistance of a GaN/AIN/Si heterojunction was studied in relation to the growth conditions of the AIN intermediate layer. Cross-sectional reflection electron microscopy (REM) images showed that the AIN intermediate layer is of pyramid-like microcrystals with a thin area in between. A clear correlation was found between the film thickness in the thin area and the apparent resistance of a sample. The growth conditions of the AIN intermediate layer were studied to achieve a low electrical resistance, maintaining the mirror flat surface morphology of a top GaN layer.