Heteroepitaxial growth of alkali halide solid solution on GaAs(l 0 0) was studied using reflection high-energy, electron diffraction, Auger electron spectroscopy, and electron energy loss spectroscopy. In past studies, a higher, substrate temperature has been needed for the epitaxial growth of alkali halides oil semiconductor substrates. We could grow it single-crystalline alkali halide thin film oil a semiconductor substrate at room temperature, Using a solid solution,1011 NaCl0.94Br0.06 whose lattice constant was equal to that of GaAs. We could modify the lattice constant of a solid solution by changing the mixing ratio, and controlling the conditions of epitaxial growth. This technique is very useful, and it can be applied to many systems. especially for the system where a severe lattice matching condition is required. (C) 2002 Elsevier Science B.V. All rights reserved.