Abstract
Treatment of GaN with SiH 4 and NH 3 increases the size of surface pits associated with threading dislocations, allowing them to be easily imaged by atomic force microscopy. Here, we assess the effect of a similar treatment on Al x Ga 1− x N surfaces for x ≤ 0.4. For relaxed Al x Ga 1− x N epilayers, an increase in the observed size and density of threading dislocation pits is observed. However, if the Al x Ga 1− x N is under tensile strain, the treatment results in the appearance of nanometre-scale surface hillocks. These hillocks may prevent observation of the dislocation pits. The hillocks are found to consist of crystalline Al x Ga 1− x N, and hence are suggested to be formed by strain driven etching or transformation of the surface by SiH 4 and NH 3.
Published Version
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