A study of nucleation in chemically grown epitaxial silicon films using molecular beam techniques

Abstract Epitaxial silicon layers have been grown on (III) silicon substrates by the pyrolysis of silane using a molecular-beam method (Joyce and Bradley 1966). The initial vacuum was 3 × 10−9 mm Hg, the substrate temperature 845°c, and the beam intensity 6 × 10−16 molecules cm−2 sec−1. The initial nucleation and growth process was studied, mainly by the transmission electron microscope method. When a ‘clean’ growth system was used, regular growth centres occurred and no crystallographic defects formed. When the system was contaminated with hydrocarbon vapours, many of the growth centres were irregular and in twin orientation. The geometry and crystallography of the twin centres are described, and the reason for the twinning is discussed.