Multiple quantum well samples, with strain-layer thicknesses larger/less than the critical one, were investigated by means of temperature-dependent photoluminescence, transmission electron microscopy and double crystal X-ray diffraction. In samples with a strained-layer thickness greater than the critical thickness, a high density of threading dislocations was observed to be generated at the multiple quantum well layers and extend into the cap layer. These dislocations resulted from relaxation of the strain layer, when its thickness was beyond the critical thickness. For samples with a strained-layer thickness greater than the critical thickness, temperature-dependent photoluminescence measurements indicated that dislocations generated from the multiple quantum well layers, due to strain relaxation, were the main reason for the poor photoluminescence properties. A status change of the main peak, with increasing temperature, was attributed to a change in radiative recombination from areas which included dislocations to ones which excluded dislocations.

Effect of Misfit Dislocation Originated from Strained Layer on Photoluminescence Properties of InxGa1-xN/GaN Multiple Quantum Wells. W.Lu, D.B.Li, C.R.Li, G.Chen, Z.Zhang: Chinese Physics Letters, 2005, 22[4], 971-4