Molecular-beam epitaxial growth of TlxIn1-xAs has been performed on InAs substrates at substrate temperatures between 150 and 250 degrees C. Optical microscopy revealed that Tl droplets decrease in size and in density with decreasing growth temperature, and vanish at lower temperatures than 175 degrees C. Secondary ion mass spectrometry (SIMS) revealed that Tl concentration shows almost flat depth profiles in the samples grown at 150-175 degrees C, but shows concave profiles in the samples grown at 200-225 degrees C. Electron probe micro analysis (EPMA) as well as SIMS showed that the Tl mole fraction x in the samples grown at 150-175 degrees C increases up to 2.7% almost in proportion with Tl flux. X-ray diffraction and cross-sectional transmission electron microscopy studies showed that monocrystalline growth is prevented if the beam equivalent pressure ratio of Tl/In is beyond 4%. (c) 2006 Elsevier B.V. All rights reserved.