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.