Photoluminescence of Tensile Strained, Exactly Strain Compensated, and Compressively StrainedSi1−x−yGexCyLayers on Si

Abstract

Band edge related photoluminescence is observed from strain compensated ${\mathrm{Si}}_{1\ensuremath{-}x\ensuremath{-}y}{\mathrm{Ge}}_{x}{\mathrm{C}}_{y}$ multiple quantum wells. For $(87\ifmmode\pm\else\textpm\fi{}4)\AA{}$ thick quantum wells, the no-phonon energy decreases linearly with increasing C content as $\ensuremath{-}y(6.8\mathrm{eV})$. The band gap for unstrained ${\mathrm{Si}}_{1\ensuremath{-}y}{\mathrm{C}}_{y}$ material is deduced for carbon concentrations lower than 0.85%. An initial energy increase and a subsequent energy decrease on the way from tensile strained ${\mathrm{Si}}_{1\ensuremath{-}y}{\mathrm{C}}_{y}$ and from compressively strained ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ alloys towards exactly strain compensated ${\mathrm{Si}}_{1\ensuremath{-}x\ensuremath{-}y}{\mathrm{Ge}}_{x}{\mathrm{C}}_{y}$ structures is measured. The different band alignments and strain-induced electron and hole level crossing effects are discussed.