A one-dimensional SiGe superlattice grown by UHV epitaxy

Abstract

One-dimensional SiGe superlattices with periods ranging from 100 to 800 Å have been deposited on Si substrates by periodically varying the Ge content of a mixed Si_1-x Ge _x multilayer structure fromx=0 tox=0.15. The deposition was successful, employing and UHV evaporation technique at a substrate temperature of 750°C fulfilling the four conditions: Single crystal growth, no interdiffusion, two-dimensional growth, and pseudomorphic growth. It is shown that mismatch above 8 · 10⁻³ favours growth by three-dimensional nucleation. The experimentally determined spacing of misfit dislocations is compared with theoretical results obtained by van der Merwe. The pseudomorphic growth behaviour of layers thinner than a critical thickness could be confirmed.