The formation mechanism of misfit dislocations of GaAs/InGaAs multi-quantum well structures was investigated by means of photoluminescence microscopy using scanning near-field optical microscopy. In the photoluminescence images, dark lines appeared along both [110] and [¯110] directions. From a comparison with the surface topographic images, it was found that these dark lines corresponded to misfit dislocations, which gave rise to non-radiative recombination centers in the InGaAs well. The density of dark lines in the <110> directions, as a function of the total layer thickness, revealed the existence of 2 critical layer thicknesses for the formation of misfit dislocations. The 2 distinct critical thicknesses were explained in terms of the modified Matthews-Blakeslee model; in which a lattice frictional force proportional to the In mole fraction was taken into account.

Formation of Misfit Dislocations in GaAs/InGaAs Multiquantum Wells Observed by Photoluminescence Microscopy. Y.Ohizumi, T.Tsuruoka, S.Ushioda: Journal of Applied Physics, 2002, 92[5], 2385-90