LOW SUBSTRATE-TEMPERATURE MOLECULAR-BEAM EPITAXIAL-GROWTH AND THE CRITICAL LAYER THICKNESS OF INGAAS GROWN ON GAAS

We report on the critical layer thickness of In(x)Ga1-xAs on GaA grown at low substrate temperatures in a wide range of indium compositions. Compared with ordinary growth conditions, the transition between pseudomorphic and relaxed regions (in the epilayer thickness versus x plane) occurred at higher indium compositions when the growth temperature was lowered. An increase in critical thicknesses for pseudomorphic growth by at least a factor of seven for alloy compositions with less than 45% indium was observed. This was determined by low temperature photoluminescence spectroscopy and transmission electron microscopy measurements on single quantum wells.