OPTICAL-PROPERTIES OF ZN1-XCDXSE-ZNSE SUPERLATTICES GROWN BY METAL-ORGANIC VAPOR-PHASE EPITAXY

An investigation of the reflectivity and photoluminescence spectra of 40-period Zn1-xCdxSe-ZnSe strained layer superlattices is reported. Su perlattices with cadmium composition between 3% and 10% were grown by metal organic vapour phase epitaxy. The well and barrier widths were v aried in order to study the tunnelling effect in the superlattices. Th is effect was shown to be large not only for the excited states (e(2)h h(2) transitions for the 10% cadmium composition) but also for e(1)hh( 1) transitions despite the large heavy hole effective mass. The band d iscontinuities were determined by calculating the transition energies within the envelope function framework generalized to strained layers. It was found that for all superlattices the mechanical state is pseud omorphic and that the heavy hole band offset is 32% of the energy diff erence of the strained band gaps. The binding energies and the oscilla tor strengths of the various excitonic transitions were calculated wit hin the formalism of fractional-dimensional space and compared with va riational calculations reported in the literature.