Structure of epitaxial PbSe grown on Si(111) and Si(100) without a fluoride buffer layer

Abstract

Epitaxial growth of PbSe on (111)- and (100)-oriented Si substrates without an intermediate buffer layer is studied. It is found that on Si(111) the orientation of the IV-VI layer can by varied from (100) at 200 °C to (111) at 400 °C substrate temperature. On Si(100), only (100)-oriented layers were obtained for the whole temperature range. (100)-oriented layers with thicknesses above 0.5 μm were cracked due to thermally induced mechanical strain on cooldown to room temperature. This strain cannot be relaxed by dislocation glide in the first glide systems as it is the case for (111)-oriented layers. The structural quality of (100)-oriented PbSe layers on Si(100) and Si(111) is inferior compared to layers grown with an intermediate BaF2/CaF2 or CaF2 buffer layer. This implies that the covalent/ionic PbSe/Si interface seems to impede high-quality epitaxy, contrary to the well known ionic/ionic IV-VI/IIa-fluoride interface.