Growth of (111)-oriented PbTe films on Si(001) using a BaF2 buffer

Epitaxial PbTe(111) films are prepared by hot-wall-beam epitaxy on Si(001) substrates using a BaF2(111)buffer layer grown by molecular beam epitaxy. According to reflection high energy electron diffraction (RHEED) analysis, the growth of BaF2(111) on Si(001) is two-dimensional with twins related to two equivalent epitaxial orientations. The twins cannot be avoided by varying the growth conditions. The PbTe (111) films repeat the twinned structure of the BaF2 buffer, with the PbTe [11(2) over bar] axis aligned along one of the Si[110] directions. The surface morphology and the carrier mobility of the PbTe films depend strongly on the growth temperature of the BaF2 buffer layer. These heterostructures exhibit electron mobilities up to 1600 cm(2)/V s (300 K) and 24 000 cm(2)/V s (77 K) and an excellent ability for the relaxation of thermal strains. (C) 2000 Elsevier Science S.A. All rights reserved.