Temperature dependence of the fundamental band gap parameters in cadmium-rich ZnxCd1-xSe using photoluminescence spectroscopy

Thin films of ternary Zn_xCd_1-xSe were deposited on GaAs (100) substrate using metalorganic-chemical-vapour-deposition (MOCVD) technique. Temperature dependence of the nearband-edge emission from these Cd-rich Zn_xCd_1-xSe (forx = 0025, 0.045) films has been studied using photoluminescence spectroscopy. Relevant parameters that describe temperature variation of the energy and broadening of the fundamental band gap have been evaluated using various models including the two-oscillator model, the Bose-Einstein model and the Varshni model. While all these models suffice to explain spectra at higher temperatures, the two-oscillator model not only explains low temperature spectra adequately but also provides additional information concerning phonon dispersion in these materials.