Direct epitaxial growth on silicon has advantages when fabricating monolithic integrated infrared focal‐plane arrays. We demonstrated that both (111)A and (111)B oriented CdTe layers can be grown on (100) Si substrates by molecular‐beam epitaxy. The surface morphology of the (111)A layer was rough, while that of the (111)B layer was smooth. The key determining polarity is the substrate temperature during preadsorption of Te2flux. We found a polarity transition at 450 to 500 °C, and (111)B layers grow above that temperature. ©1995 American Institute of Physics.