Properties and applications of MBE‐grown (111) CdTe films on (0001) sapphire substrates are discussed. From Laué diffraction studies, the epitaxial orientation relationships are (111)CdTe∥ (0001) sapphire, with [11̄0]CdTe∥[112̄0] sapphire. On the basis of these results, an atomic model of the CdTe/sapphire interface is proposed and discussed. As‐grown p‐type films convert to n type upon heating in a Cd atmosphere and become highly conducting. Hall mobilities greater than 1000 cm2/V s at room temperature have been obtained for Cd‐annealed films. CdTe epilayers have also been successfully used as substrates for growth of HgCdTe by the close‐spaced vapor transport technique. As‐converted Hg0.83Cd0.17Te films exhibit intrinsic conduction down to about 150 K. These n‐type layers have carrier concentrations of 8×1015/cm3 and electron mobilities greater than 2×105 cm2/V s at 77 K.