Synthesis and Optical Characterization of Cu-Doped ZnS Phosphors

• Main Authors: Jhen-Jyue Wang, 王振爝
• Other Authors: Yu-Tai Shih
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/71647660717371597741

碩士 === 國立彰化師範大學 === 光電科技研究所 === 96 === Cu-doped ZnS phosphors were synthesized by solid-state reaction method. The structure, grain size, doping concentration, and optical properties of these phosphors were determined by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray energy dispersive spectrometer (EDS), photoluminescence (PL) and photoluminescence excitation (PLE) measurement. The XRD results showed the structure of the ZnS:Cu phosphors is zinc-blende. The EDS results showed the Cu concentration in host ZnS crystals was similar to that in preparation. From the PL spectra, two blue band were observed. One with emission peak at 447 nm was attributed to the interstitial Cu impurities. The other was a self-activated blue band with peak at 477 nm. It was attributed to the defects in ZnS crystals, such as vacancies and dislocations. The optimal Cu concentration for best luminescence intensity was 1.5 %. The temperature-dependent PL spectra displayed the luminescence intensity of blue and self-activated band increased initially and then decreased as the temperature increased. This temperature dependence was attributed to the precipitation of CuxS at surface of ZnS crystals and the formation of CuxS/ZnS junction. As the temperature increased, lots of excess carries were injected into host crystals, so that the luminescence which results from the interstitial Cu and self-activated enhanced. The color of luminescence from the ZnS:Cu phosphors changed from purple to blue as the temperature increased.