The evolution of surface roughness, and plastic relaxation mechanisms, were studied by means of transmission electron microscopy for various thicknesses of highly strained GaInAs layers on GaAs(001). Three stages were observed. These were the formation of coherent islands, the coalescence of islands, and the nucleation of dislocations at the troughs of the surface ripples. Dislocations were systematically generated where the highest stress concentrations were expected to exist, according to theoretical predictions. It was noted that this was the first time that such a plastic relaxation mechanism had been observed in highly strained semiconductor heterostructures.

Y.Androussi, A.Lefebvre, C.Delamarre, L.P.Wang, A.Dubon, B.Courboulès, C.Deparis, J.Massies: Applied Physics Letters, 1995, 66[25], 3450-2