Optical investigation of confinement and strain effects in CdTe/Cd1−xZnxTe single quantum wells

Abstract

Transmission, luminescence, and excitation spectra are presented for strained ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Zn}}_{\mathrm{x}}$Te/CdTe/${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Zn}}_{\mathit{x}}$Te quantum-well heterostructures grown by molecular-beam epitaxy with CdTe thicknesses ranging from 1000 to 50 Å. The effect of carrier confinement in such quasibidimensional systems is shown by substantial energy shifts of excitonic transitions related to the existence of quantized states. The structures are of mixed type with electrons and heavy holes confined in the CdTe wells (type I), whereas the light holes are localized in the ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Zn}}_{\mathrm{x}}$Te barriers (type II). These results also allow an estimation of the variation with thickness of the 2D-exciton binding energy.