Growth mechanism of cuboid growth pits in lead selenide epilayers grown by molecular beam epitaxy

摘要

Microstructures and crystallographic orientations of cuboid growth pits in lead selenide (PbSe) epilayers grown on Si (1 1 1) by molecular beam epitaxy (MBE) have been studied by scanning electron microscopy and cross-sectional transmission electron microscopy. Cuboid density was found to be dependent on MBE growth parameters such as sample thickness and substrate temperature. Cuboid growth defects nucleate spontaneously on the PbSe growth surface probably at Pb droplets. This nucleation results in randomly oriented PbSe crystallites that preferentially grow along the [1 0 0] axis of the NaCl-type crystal structure. This preferential growth results in cuboid crystallites with cubic faces protruding from the epitaxial (1 1 1) face.