Photoluminescence measurements were used to investigate the intermixing behavior of GaAs/Ga0.65Al0.35As multiple quantum wells, due to heat treatment. The photoluminescence spectra of annealed samples comprised step-like signals, and showed that the degree of intermixing of Al and Ga that was induced by the annealing of these multiple quantum wells differed according to the depth. Photoluminescence spectra which were obtained by using layer-by-layer chemical etching showed that atomic mixing was greatest near to the sample surface, and decreased monotonically with depth. This was attributed to varying distributions of the diffused Ga vacancy. The potential profile of the GaAs/Ga0.65Al0.35As as a function of the diffusion length was investigated, and electron and hole energy sub-bands in the multiple quantum wells were calculated by using a variational method that used the calculated potential profile. The Ga vacancy concentration which corresponded to depth in the multiple quantum wells was estimated from the Al interdiffusion length and from the distribution of diffused Ga vacancies. This indicated that the diffusion length of Al was proportional to a logarithmic function of the Ga vacancy concentration.

Y.T.Oh, T.W.Kang, C.Y.Hong, K.T.Kim, T.W.Kim: Solid State Communications, 1995, 96[4], 241-4