Spin-flip Raman scattering in CdTe/${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te multiple quantum wells: A model system for the study of electron-donor binding in semiconductor heterostructures

The spin-flip Raman scattering of electrons bound to donors in CdTe/${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Te multiple-quantum-well structures at 1.6 K in magnetic fields up to 6 T has been studied for a range of samples forming two series in which, first, the CdTe quantum-well width and second, the ${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Te barrier composition x were varied systematically. For structures with x<0.1, two spin-flip Raman bands are observed, which can be assigned to electrons located in the quantum wells and bound to donors located either in the quantum wells themselves or in the barriers of the structure. Measurements of the excitation spectra of the two Raman bands and of the quantum-well photoluminescence support this assignment. A variational calculation allows us to simulate the form of the observed spectra and also gives a quantitative description of the dependence of the Raman peak positions on the well width and barrier composition. The calculation allows us to derive a value of 0.060±0.005 eV for the conduction-band offset when x=0.07.