GAP ENERGIES, EXCITON BINDING-ENERGIES AND BAND OFFSETS IN TERNARY ZNMGSE COMPOUNDS AND ZNSE ZNMGSE HETEROSTRUCTURES/

Measurements of optical and photoelectron spectra are presented to det ermine tile band offsets of ZnSe/Zn1-xMgxSe heterostructures. The samp les are grown on GaAs(001) by MBE and investigated by absorption, phot oreflection, photoluminescence, photoluminescence-excitation and photo -electron spectroscopy using a synchrotron light source. Ln the visibl e spectra discrete excitonic states are observed at the E-0 and E-0 Delta(0) gap up to a composition of x less than or equal to 0.36. The optical transitions of ZnSe/Zn1-xMgxSe single quantum wells are fitted to a model. It contains the conduction band offset as the only free p arameter, which is then determined by a least-squares fit of the data. Photoelectron spectra (UPS) are measured on ZnSe which was in situ de posited on MgSe in several monolayer thickness. The valence band edges of ZnSe and MgSe are simultaneously observable and thus a direct dete rmination of the valence band offset was possible. The values of the b and offsets from the two different methods agree reasonably well withi n the errors of the measurements. Different from other systems ZnSe/Zn 1-xMgxSe does not fulfil the common anion rule, which may be due to ti le filled d-shell of Zn which is lacking in Mg.