Acceptor dopants in silicon molecular‐beam epitaxy

摘要

Epitaxial silicon films have been grown on single‐crystal Si (100) substrates by evaporation from an e‐gun source in ultrahigh vacuum and have been doped with gallium and with aluminum from separate oven sources. Gallium doping profiles have been controlled accurately for substrate temperatures in the range 600–800 °C and for carrier densities in the range 1014–5×1017 cm-3. Examples are given of abrupt changes in doping level. Measured drift mobilities in the films are within 15% of values for bulk silicon. Crystallographic properties of the films are comparable to those of the substrates and are suitable for device applications. Films doped with aluminum exhibit comparable electrical and crystallographic properties, but good control of the doping profile has not been achieved for the range of parameters studied.