Band-edge and deep level photoluminescence of pseudomorphic Si1−xyGexCy alloys

Abstract
Photoluminescence of strained Si1−xyGexCy 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−xyGexCy 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.