RADIATIVE RECOMBINATION IN MBE-PREPARED EPITAXIAL SI AND SI1-XGEX LAYERS

Examination of near-gap low-temperature photoluminescence (PL) from epitaxial, MBE-prepared Si and Si1-xGe(x) alloys, prepared commensurately to (001) 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.