A comparative study was made of the spatial distributions of electrical, optical and structural properties in an AlGaN/GaN heterostructure. The edge dislocation density in the GaN template layer was shown to decrease in regions of the wafer where the heterostructure sheet resistance increased and the GaN photoluminescence band-edge energy peak shifted to a high wavelength. This was found attributed to the local compressive strains surrounding edge dislocations; which could generate a local piezo-electric polarization field in the GaN layer, in the opposite direction to the piezo-electric polarization field in the AlGaN layer.

Influence of Dislocations in the GaN Layer on the Electrical Properties of an AlGaN/GaN Heterostructure. Z.Y.Gao, Y.Hao, J.C.Zhang, P.X.Li, W.P.Gu: Chinese Physics B, 2009, 18, 4970