The compositional disordering of GaAs/AlGaAs quantum wells, due to the presence of low-temperature molecular beam epitaxially grown GaAs, was studied. It was found that Ga vacancy-enhanced interdiffusion was the mechanism which was responsible for the observed intermixing. The diffusion equations were solved numerically in order to obtain the band profile after intermixing. The transition energies in the quantum wells under various annealing conditions were predicted, and were found to agree very well with observed photoluminescence emission peaks. The vacancy-induced interdiffusivity was found to require an activation energy of 4.08eV. This was smaller than the activation energy for the interdiffusion of GaAs/AlGaAs heterostructures which were grown at normal temperatures. It was concluded that the present results clearly indicated an enhanced interdiffusion that was due to the presence of GaAs which had been grown at low temperatures.

J.S.Tsang, C.P.Lee, S.H.Lee, K.L.Tsai, H.R.Chen: Journal of Applied Physics, 1995, 77[9], 4302-6