Surfactant effect of bismuth in atmospheric pressure MOVPE growth of InAs layers on (100) GaAs substrates

InAs layers have been grown on GaAs substrates with and without bismuth flow, at a growth temperature of 450 degrees C and a V/III ratio of 18, by atmospheric pressure metal-organic vapor phase epitaxy. Thickness measurements using scanning electron microscopy show that bismuth reduces the growth rate. Atomic force microscopy images show the presence of Bi islands inlayed in InAs layer degrading its surface morphology. High resolution X-ray diffraction curves confirm that bismuth does not incorporate into InAs layers but improves the crystalline quality by reducing the dislocation density. This improvement is attributed to Bi nanodots contributing to the strain relaxation. Room temperature Hall effect measurements have evidenced that growing InAs under Bi flow increases the electron mobility. Therefore Bi acts as a surfactant during growth of InAs layers on GaAs substrate. (c) 2010 Elsevier B.V. All rights reserved.