A study was made of the origin of spatial luminescence fluctuations which were observed between dark-line defects in tensile-strained heterostructures. Semi-quantitative and spectroscopic cathodoluminescence measurements of various specimens in areas which exhibited a cathodoluminescence contrast which could be as high as 80%. An analysis of the variation in cathodoluminescence as a function of the electron beam energy permitted information to be obtained on the diffusion-recombination parameters of the areas in question. On the basis of the correlation between the local relaxation levels in these areas, and their diffusion-recombination parameters, it was concluded that variations in the misfit dislocation density at the GaInP/InP interface were at the origin of the luminescence heterogeneities. It was also demonstrated that recycling, by the GaInP epilayer, of photons which originated from the heavily-doped InP substrate, enhanced the cathodoluminescence contrast between areas which exhibited differing relaxation levels.

F.Cléton, B.Sieber, A.Bensaada, R.A.Masut, J.M.Bonard, J.D.Ganière: Journal of Applied Physics, 1996, 80[2], 837-45