Visible photoluminescence from nanocrystalline Ge formed by H2 reduction of Si0.6Ge0.4O2

Abstract

Samples of nanocrystalline Ge embedded in SiO2 that display visible photoluminescence were synthesized from chemical vapor deposition-grown Si0.6Ge0.4 in a two step process of hydrothermal oxidation using steam at 25 MPa and 475 °C followed by annealing at 750 °C in flowing forming gas (80/20:N2/H2). A broad photoluminescence band, peaked at 2.14 eV (580 nm) with a full width at half maximum of 0.3 eV, was observed in samples that were annealed at 750 °C in flowing forming gas for 10, 30, and 60 min. As-oxidized (i.e., unprecipitated) samples show no photoluminescence peak when excited under identical conditions.