Multi quantum-well structures and bulk InGaN films which had been grown onto (00•1) sapphire substrates were investigated by means of cross-sectional transmission electron microscopy and double-crystal X-ray diffraction. Highly-strained InGaN layers with a high In mole fraction were found to contain V-shaped surface pits with (10•1) facet planes on pure or mixed screw threading dislocations. The mechanism of surface pit formation was explained in terms of strain energy and surface mobility on InGaN.

Formation of V-shaped pits in InGaN/GaN multiquantum wells and bulk InGaN films I.H.Kim, H.S.Park, Y.J.Park, T.Kim: Applied Physics Letters, 1998, 73[12], 1634-6