InAs layers grown by molecular beam epitaxy at 150-350 degrees C were characterized by electron probe microanalysis (EPMA), high resolution X-ray diffraction (HRXRD), Hall measurements, and secondary ion mass spectrometry (SIMS). EPMA revealed that the As mole fractions in the layers grown at 150-200 degrees C are higher by about 0.5% than those in the layers grown at 300-350 degrees C. HRXRD measurements revealed that the layers grown at 150-200 degrees C have larger lattice spacings than the InAs substrate by about 0.02%. Hall measurements revealed that the free-electron concentration in the layer grown at 200 degrees C is as high as 1.4 x 10(19) cm(-3) while such a high concentration of impurities cannot be detected by SIMS. Upon annealing at higher temperatures than 250 degrees C, both the lattice spacing and the free-electron concentration of the layer grown at 200 degrees C were observed to decrease. These phenomena can be reasonably attributed to antisite As. (c) 2006 Elsevier B.V. All rights reserved.