Interaction of low-temperature surfactant-grown InAs superlattice layers with arsenic precipitates
Double crystal X-ray diffraction (DCXRD), transmission electron microscopy (TEM) and photoluminescence (PL) measurements were used to study the effect of post-growth annealing temperature on the structural properties of novel low growth (250C) and normal growth (450C) temperature InAs surfactant-mediated grown materials. Under conditions of arsenic-free growth, high-quality InAsGaAs superlattices are obtained at low temperatures (LT) even at thicknesses as high as 3 monolayers (MLs) for InAs. The interaction of the built-in strain fields and the point defects in LT-GaAs both before and after annealing has been studied in detail. DCXRD studies show that the thickness of the LT-grown InAs layers decreased by up to 0.7ML as the annealing temperature increased to 550C. There is evidence from the DCXRD and TEM that the LT InAsGaAs superlattice structure starts to distort at annealing temperatures above 450C. In comparison, the sample grown at normal temperature, 450C, still retained the periodicity of the superlattice layers up to an annealing temperature of 650C without any change in the thickness of either the InAs (wetting layer) or GaAs.
arsenic precipitates molecular beam epitaxy low-temperature growth inas quantum dots