Structural and chemical defects were identified which resulted from the epitaxial growth of layers. Transmission electron microscopy, annular dark-field imaging, energy-filtered transmission electron microscopy and X-ray mapping were used to study multiple quantum-well structures which were capped with a p-type GaN layer. Transmission electron microscopy and annular dark-field imaging studies of the samples revealed a number of V-defects which were spaced some 100 to 200nm apart along the multiple quantum well. Each V-defect incorporated a pure edge (1/3<11•0>) dislocation, which ran through the apex of the V-defect and up to the free surface. These V-defects contained GaN with no InGaN layers; thus suggesting that the capping layer had filled in the open V-defects.

Chemical Mapping of InGaN MQWs. N.Sharma, D.Tricker, P.Thomas, Z.Bougrioua, K.Jacobs, J.Cheyns, I.Moerman, T.Thrush, L.Considine, A.Boyd, C.Humphreys: Journal of Crystal Growth, 2001, 230[3-4], 438-41