Abstract
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 (250 degrees C) and normal growth (450 degrees C) temperature InAs surfactant-mediated grown materials. Under conditions of "arsenic-free" growth, high-quality InAs-GaAs 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 0.7 ML as the annealing temperature increased to 550 degrees C. There is evidence from the DCXRD and TEM that the LT InAs-GaAs superlattice structure starts to distort at annealing temperatures above 450 degrees C. In comparison, the sample grown at normal temperature, 450 degrees C, still retained the periodicity of the superlattice layers up to an annealing temperature of 650 degrees C without any change in the thickness of either the InAs (wetting layer) or GaAs. (c) 2008 Elsevier Ltd. All rights reserved.