Optical properties of CdTe/${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$Te strained-layer single quantum wells

The electronic states in a series of molecular-beam-epitaxy-grown CdTe/${\mathrm{Cd}}_{0.79}$${\mathrm{Zn}}_{0.21}$Te strained-layer single quantum wells have been studied both theoretically and experimentally. Calculations based on model solid theory and deformation-potential theory have shown that, at Zn concentration of 0.21 in the barriers, the band lineup is type I for heavy holes and type II for light holes. The confined states were calculated using the three-band envelope function model. Photoluminescence measurement at temperatures between 9 and 100 K indicates that the broadening mechanism is dominated by the polar optical phonon (longitudinal optical) interactions. The circularly polarized excitation spectra have shown predominant heavy-hole feature confirming that the band lineup is type I for heavy holes and type II for light holes. With well width between 25 and 75 Å, our study has shown that exciton binding energy decreases with decreasing well width.