An investigation was made, using a 2-stage Zn diffusion and thermal annealing process, of impurity-induced disordering in strained samples of InxGa1-xAs/GaAs single quantum well heterostructures, where x ranged from 0.21 to 0.24. The samples were grown by means of metalorganic vapor-phase epitaxy, and various shallow Zn diffusion depths were produced in the GaAs cap layer in order to vary the Zn concentration in the quantum wells. Thermal annealing (785C, 600s) in an AsH3/H2 atmosphere then produced impurity-induced disordering. Partially disordered and completely disordered quantum well heterostructures were studied, and In-Ga interdiffusion was monitored via the photoluminescence spectroscopy of ground state emissions from the quantum wells. The interdiffusion coefficients (table 36) were determined by applying the envelope function to shifts in the photoluminescence peak position during annealing. It was found that the interdiffusion coefficient was very strongly dependent upon the Zn diffusion depth, and therefore upon the Zn concentration in the quantum well layer. A model was proposed that used an interstitial migration process to explain the enhancement of In-Ga interdiffusion by Zn diffusion.

M.T.Furtado, M.S.S.Loural, E.A.Sato, M.A.Sacilotti: Semiconductor Science and Technology, 1992, 7[6], 744-51

Table 36

Interdiffusion Coefficients for InxGa1-xAs/GaAs