Single phase Ca2Si layers are successfully grown on Mg2Si/Si substrates for the first time. These Mg2Si and Ca2Si layers are formed by heat treatment of Si and Mg2Si/Si substrates in Mg and Ca vapor, respectively. The replacement of Ca atoms with Mg in Mg2Si leads to the formation of single phase Ca,Si layers. it is confirmed that the formation of other silicide phases is suppressed, when the layers are grown under optimum growth time. The structural property of the resultant layers is examined by X-ray diffraction technique, scanning electron microscopy and transmission electron microscopy. (C) 2002 Elsevier Science B.V. All rights reserved.