InAs epilayers with thicknesses of 400, 500, 750, and 1500 nm were grown on GaAs by molecular beam epitaxy and their properties were investigated by reflection high-energy electron diffraction and photo luminescence (PL). For all InAs epilayers, the PL peak position measured at 10 K is blue-shifted from that of bulk InAs, which could be largely due to the residual strain in the epilayer. InAs epilayers have PL peaks red-shifted to lower energy as the thickness of InAs layer is increased. This is the first observation on PL of sub-mum thick InAs epilayers grown on GaAs substrate. While the PL peak position of 400 nm thick InAs layer is linearly blue-shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of thicker InAs epilayers are gradually blue-shifted and then, saturated above a power of 75 mW. (C) 2002 Elsevier Science B.V. All rights reserved.