| Summary: | 碩士 === 國立彰化師範大學 === 光電科技研究所 === 93 === This thesis is devoted to the study on the optical properties of Cadmium Sulfide (CdS) crystal by taking temperature-dependent photoluminescence (PL), reflectance (R), and transmission (T) measurements. From the temperature-dependent PL spectra, a redshift of the PL peaks was observed as the temperature increased. The temperature dependence of CdS energy gap, determined from the PL spectra, was fitted according to Varshni, O’Donnell, and Pässler relations. Good fit was obtained using the Pässler relation. From the Pässler’s fit, the average phonon temperature and phonon dispersion coefficient of the CdS crystal were determined. The free exciton and bound exciton activation energies of A-exciton of the CdS crystal were determined by the plots of integrated PL intensity versus temperature. The temperature-dependent broadening of the PL linewidth was also investigated. The LA- and LO- phonon scatterings were found to be the dominant broadening mechanisms at low and high temperatures respectively. From the R and T spectra, the energies of A, B, and C excitons of the CdS crystal were identified. The R data were also used to perform the Kramers-Kronig transformation. The optical coefficients of the CdS crystal, such as the reflective index, the dielectric function, and the absorption coefficient, were determined.
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