硒化鋅及其三元,四元化合物之光學性質研究

Abstract

The optical properties of ZnSe based ternary and quaternarycompounds were invertigated by using photoluminescence (PL), reflection,and Raman spectroscopy methods. Two of ZnSe based compounds, ZnMnSeepilayers which were grown on GaAs (100) by molecular beam epitaxy (MBE)technique and ZnMnSe thin films which were grown on thin glasses byradio frequency (RF) sputtering techniuqe, were studied. Photoluminescenceand reflection measurements manifest that the energy gap increasinglinearly with Mn concentration x. Raman scattering spectroscopy of ZnMnSeepilayers and ZnMnSe thin films exhibits mixed-mode behaviors. PL and Raman spectra manifest the stress effect due to lattice mismatch wasreleased for the films with thickness larger than 1000 A. The crystalqualities can be justified by comparing the symmetry and intensity ofthe LO phonon peaks. Temperature dependence of photoluminescence spectroscopy of ZnCdSe/ZnSe based multi-quantum-well structure epilayers was also investigated. The luminescence efficiency was found to be improvedby using a wider band-gap quaternary alloy ZnMgSSe as buffer layers.The luminescence efficiency can be also improved by increasing the layers of quantum wells. The mechanism of the enhancement of the luminescence intensities for the above mentioned methods might be very different. A three-parameter simple equation was used to fit thetemperature dependence of ZnMnSe and ZnTe epilayer semiconductorband gaps. Our formula is justified both in practical and theoretical grounds. This is because our formula is shown to be compatible with reasonable assumptions for the influence of phonons on the band-gapenergy. In addition to this, the fitting result is numberically betterthan that obtained by using the widely quoted-Varshni equation.Besides, we also intorduce the evolution of fitting energy equations and justify its validation.