Low-temperature growth of self-assembled InAs dots on GaAs by molecular beam epitaxy

We report low-temperature (LT) growth of self-assembled InAs dots on GaAs by molecular beam epitaxy. Atomic force microscopy reveals well-developed InAs dots grown at LT (250 degrees C) on top of a LT GaAs bottom layer after post-growth annealing above 450 degrees C. When the InAs dots are overgrown by LT GaAs, however, X-ray diffraction reveals poor structural quality of the dot- and the LT GaAs top layers. Excellent structural quality of the InAs dots and LT GaAs top layer is achieved when the dots, before LT GaAs overgrowth, are capped with a thin (3 nm) GaAs interlayer at 480 degrees C and subsequently annealed at 580 degrees C. Realization of these high-quality InAs dots grown at low substrate temperature may be useful for ultra-fast response optical devices