Photoluminescence of Tensile Strained, Exactly Strain Compensated, and Compressively Strained ${\mathrm{Si}}_{1-\mathit{x}-\mathit{y}}{\mathrm{Ge}}_{\mathit{x}}{C}_{\mathit{y}}$ Layers on Si

Band edge related photoluminescence is observed from strain compensated ${\mathrm{Si}}_{1-x-y}{\mathrm{Ge}}_x{\mathrm{C}}_y$ multiple quantum wells. For $(87\pm 4)Å$ thick quantum wells, the no-phonon energy decreases linearly with increasing C content as $-y\left(6.8\mathrm{eV}\right)$. The band gap for unstrained ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ 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 ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ and from compressively strained ${\mathrm{Si}}_{1-x}{\mathrm{Ge}}_x$ alloys towards exactly strain compensated ${\mathrm{Si}}_{1-x-y}{\mathrm{Ge}}_x{\mathrm{C}}_y$ structures is measured. The different band alignments and strain-induced electron and hole level crossing effects are discussed.