PHOTOLUMINESCENCE OF TENSILE-STRAINED, EXACTLY STRAIN COMPENSATED, AND COMPRESSIVELY STRAINED SI1-X-YGEXCY LAYERS ON SI

Band edge related photoluminescence is observed from strain compensate d Si1-x-yGexCy multiple quantum wells. For (87 +/- 4) Angstrom thick q uantum wells, the no-phonon energy decreases linearly with increasing C content as -y(6.8 eV). The band gap for unstrained Si1-yCy material is deduced for carbon concentrations lower than 0.85%. An initial ener gy increase and a subsequent energy decrease on the way from tensile s trained Si1-yCy and from compressively strained Si1-xGex alloys toward s exactly strain compensated Si1-x-yGexCy structures is measured. The different band alignments and strain-induced electron and hole level c rossing effects are discussed.