The epitaxial growth of an alloy of CaF2 and CdF2: CaxCd1-xF2, on Si(111) substrates using a CaF2 buffer layer was investigated. When grown on a 10 nm-thick buffer layer, the optimum growth temperature of the CaxCd1-xF2 layer was found to be around 200degreesC, dependending on the composition x, as determined based on the crystallinity and surface roughness. The CaF2 buffer layer was found to be necessary for the growth of good CaxCd1-xF2 layers, and the thickness of the buffer layer was reduced to 2 monolayers while maintaining the crystallinity and surface morphology as good as that for growth on thicker buffer layers. (C) 2002 Elsevier Science B.V. All rights reserved.