Quantum-well structures were studied using magneto-optical transmission spectroscopy. The effects of dopants, overgrowth and annealing were investigated. The blue-shift effect, which was often observed in multiple quantum-well structures that were subjected to heat-treatment, was here attributed to a dominant group-V interdiffusion which could be suppressed by high defect densities in the substrate. The presence of Zn in an overgrown layer on top of the multiple quantum-well structures caused a counteractive red-shift effect after long annealing times. This was due to group-III diffusion. On the other hand,  in situ  Zn or S produced no observable shift in transition energies due to interdiffusion. This was attributed to an enhanced group-III interdiffusion that was induced by Zn diffusion into the multiple quantum-wells. It was concluded that very different interdiffusion mechanisms operated in the case of group-III and group-V elements; thus supporting the suggestion of vacancy-related group-V interdiffusion rather than the interstitialcy mechanism of group-III interdiffusion.

S.L.Wong, R.J.Nicholas, R.W.Martin, J.Thompson, A.Wood, A.Moseley, N.Carr: Journal of Applied Physics, 1996, 79[9], 6826-33