Excitonic properties and band alignment in lattice-matched ZnCdSe/ZnMgSe multiple-quantum-well structures

Lattice-matched Zn(0.85)Cd(0.15)Se/Zn(0.74)Mg(0.26)Se multiple-quantum-well structures were obtained on GaAs (001) using graded-composition In(y)Ga(1-y)As layers to match the II–VI lattice parameter to the III–V substrate. Cross-sectional transmission electron microscopy studies show that the effect of the crosshatch pattern of the In(y)Ga(1-y)As surface is limited to long-period coherent undulations of quantum well and barrier layers. Optical measurements of the excitonic properties as a function of well thickness, complemented by self-consistent calculations of the transition energies, indicate good quantum confinement in the well, with a 68% conduction band contribution to the 0.482 eV band gap difference.