Early-stage growth of GeTe on Si(111)-Sb

The advent of germanium telluride as a promising ferroelectric Rashba semiconductor for spintronic applications requires the growth of nanometer-thick films of high crystalline quality. In this study, we have elucidated the initial growth stages of GeTe on Si(111)-Sb by scanning tunneling microscopy and low energy electron diffraction. We demonstrate the presence of an initial 0.35-nm-thick GeTe buffer layer followed by the 2D growth of GeTe via Frank-Read sources of atomic steps. As shown by core level spectroscopy, Sb is acting as a surfactant during growth up to a 5-nm-thick film. X-ray diffraction, transmission electron microscopy, and low energy electron microscopy evidence that numerous mirror domains and in-plane misorientations appear early in the growth process and are gradually buried at the film/substrate interface. The use of a miscut Si substrate close to Si(111) allows suppressing these defects from the early beginning of growth.