Band lineup in ${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Sb}}_{\mathrm{x}}$/GaAs strained-layer multiple quantum wells grown by molecular-beam epitaxy

${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Sb}}_{\mathrm{x}}$/GaAs strained-layer multiple quantum wells have been grown by molecular-beam epitaxy and characterized by room-temperature photoreflectance (PR). The PR spectra denote that high-quality layers can be grown in the ${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Sb}}_{\mathrm{x}}$/GaAs system. The method for determining the band offset $Q_{\mathrm{vh}}$ is discussed in this strained-layer system. Based on this treatment and the band-gap formula of bulk ${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Sb}}_{\mathrm{x}}$ a value of the heavy-hole band offset ($Q_{\mathrm{vh}}$∼1.7) has been obtained for ${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Sb}}_{\mathrm{x}}$/GaAs with x=0.1 establishing a type-II structure with electrons in GaAs layers and heavy and light holes in ${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Sb}}_{\mathrm{x}}$ layers, respectively.