Band-edge and deep level photoluminescence of pseudomorphic Si1−<i>x</i>−<i>y</i>Ge<i>x</i>C<i>y</i> alloys

Abstract

Photoluminescence of strained Si1−x−yGexCy alloys grown by rapid thermal chemical vapor deposition on Si(100) is investigated. Two dominant features are reported: At low pump intensities, the photoluminescence is dominated by a deep level broad luminescence peak around 800 meV whereas at high pump intensities, a well-resolved band-edge luminescence (no phonon and transverse optic replica) is observed. At 77 K, we attribute this band-edge feature to an electron-hole plasma luminescence of the ternary alloy. The dependences of the deep level and band-edge peaks versus the excitation power density are, respectively square-root-like or superlinear. A blue shift of the energy gap of Si1−x−yGexCy alloys with respect to Si1−xGex alloy is observed. The blue shift increase with carbon content corresponds to what is expected for the bulk alloy. An eventual influence of the strain relaxation cannot be excluded.