The effects of Si and Be, at doping levels of up to 1019/cm3, upon the interdiffusion of quantum wells after annealing were studied by using photoluminescence techniques (table 32). It was found that, for Be concentrations of up to 2.5 x 1019/cm3, and for Si concentrations of up to 1018/cm3, no change in the interdiffusion coefficients could be measured. At a Si dopant concentration of 6 x 1018/cm3, there was a dramatic degradation of the material quality after annealing (750C, 15s). This caused the luminescence from the well to disappear, while a deep-level luminescence that was related to donor-Ga vacancy complexes and As antisite defects appeared. On the basis of these results, it was suggested that the position of the Fermi level played no role in the intermixing of III-V heterostructures. It was also concluded that most of the enhanced intermixing which was observed in Si-doped GaAs/AlGaAs structures was related to Si relocation at very high doping levels.

W.P.Gillin, I.V.Bradley, L.K.Howard, R.Gwilliam, K.P.Homewood: Journal of Applied Physics, 1993, 73[11], 7715-9

Table 32

Interdiffusion Data for Ga0.8Al0.2As/GaAs