Crystal structure and habit of silicon and germanium particles grown in argon gas

Abstract

Silicon and germanium particles prepared by evaporation in argon at low pressure have been studied by electron microscopy. The particles are crystalline and show frequently distinct crystal habits. The typical habit of silicon particles is a {311} icositetrahedron truncated by eight {111} faces, and that of germanium particles is a {311} icositetrahedron. For germanium, multiply-twinned particles have also been found when they were prepared in a clean atmosphere. The crystallites with these habits have the ordinary diamond structure. Germanium particles with a new structure (tetragonal system, a=0.537 nm and c=0.904 nm) are also found besides those with the ordinary diamond structure. The particles with the new structure are not formed when evaporation is carried out in an atmosphere containing a small amount of air.