Rapid thermal annealing of InAs/GaAs quantum dots under a GaAs proximity cap

The effect of postgrowth rapid thermal annealing (RTA) on GaAs proximity-ca pped structures with self-assembled InAs/GaAs quantum dots (QDs) is investi gated using transmission electron microscopy (TEM) and photoluminescence (P L). As can be seen from the TEM images, QDs increase their lateral sizes wi th increasing annealing temperature (up to 700 degreesC). QDs cannot be dis tinguished after RTA at temperature 800 degreesC or higher, and substantial thickening of the wetting layer can be seen instead. The main PL peak blue shifts as a result of RTA. We propose that in the as-grown sample as well, as in samples annealed at temperatures up to 700 degreesC, the peak is due to the QDs. After RTA at 800 degreesC and higher the PL peak is due to a mo dified wetting layer. Relatively fast dissolution of QDs is explained in te rms of strain-induced lateral Ga/In interdiffusion. It is proposed that suc h a process may be of importance in proximity-capped RTA, when no group-III vacancy formation takes place at the sample/capping interface. (C) 2001 Am erican Institute of Physics.