Radiative recombination in MBE-prepared epitaxial Si and Si_1-xGe_x layers

Examination of near-gap low-temperature photoluminescence (PL) from epitaxial, MBE-prepared Si and Si1-xGex alloys, prepared commensurately to (0 0 1) Si, failed to show either free excitons or dopant- bound-excitons in as-prepared layers. Significant luminescence was, however, successfully induced by the selective introduction of two well-known, and moderately shallow, radiation-damage centers (I1 and G) into these epi-layers. Both centers exhibit alloy broadened spectra which, together with detailed PL intensity vs etch depth, indeed demonstrate that the radiative defects are contained well-within the epitaxial layers. © 1991.