The migration of Al and Ga in Ga0.6Al0.4As/GaAs quantum wells was investigated by measuring the photoluminescence of samples which had been annealed at temperatures ranging from 850 to 1065C; with and without a SiO2 cap. At 1000C, under a SiO2 cap, the Al-Ga interdiffusion coefficient was at least 2 orders of magnitude higher for a GaAlAs/GaAs quantum well than for an InAlGaP/GaInP quantum well, within the same sample. By comparing the calculated photoluminescence shifts with measured values, an activation energy of 4.5eV was estimated (table 6) for Al-Ga interdiffusion in a GaAlAs/GaAs quantum well under a SiO2 cap.

K.J.Beernink, D.Sun, D.W.Treat, B.P.Bour: Applied Physics Letters, 1995, 66[26], 3597-9

Table 6

Interdiffusivity (Al-Ga) in GaAlAs/GaAs