ZnS薄膜生长温度对ZnS／PS体系结构和发光的影响

Effect of growth temperature of ZnS films on the structure and luminescence properties of ZnS/PS composite systems

用电化学阳极氧化法制备了一定孔隙率的多孔硅(PS,PorousSilicon)样品,然后以PS为衬底用脉冲激光沉积(PLD)的方法在100℃、200℃和300℃下生长ZnS薄膜。X射线衍射(XRD)结果表明,样品都在28.5°附近有一个较强的衍射峰,对应于β-ZnS(111)晶向,说明薄膜沿该方向择优取向生长,但由于衬底PS粗糙的表面结构,衍射峰的半高全宽(FWHM)较大。随着ZnS薄膜生长温度的升高,薄膜的衍射峰强度逐渐增强。扫描电子显微镜(SEM)像显示,随着薄膜生长温度的升高,构成薄膜的纳米晶粒生长变大。室温下的光致发光(PL)谱表明,随着薄膜生长温度的升高,ZnS的发光强度增强而PS的发光强度减弱,把ZnS的蓝绿光与PS的红光叠加,在可见光区450～700nm形成了一个较宽的光致发光谱带,呈现较强的白光发射。

Porous silicon （PS） sample with certain porosity was prepared by electrochenical anodization of p type silicon wafer, and ZnS films were deposited on the PS substrate at different temperatures （100 ℃ ,200 ℃ ,300 ℃ ）by pulsed laser dep osition （PLD）. X-ray diffraction （XRD） patterns showed that,all samples had a diffraction peak at about 28.5°corresponding to β-ZnS （111） direction, which indicated that ZnS films were grown in preferred orientation along this direction, but the full width at half maximum （FWHM） of the diffraction peak was large due to the roughness of the PS surface. With the increase of growth temperature, the diffraction peak intensity of ZnS films increased. Scanning electron microscope （SEM） images showed that,the crystalline grain of ZnS films grew larger with the increase of growth temperature. The photoluminescence （PL） spectra of ZnS/PS composites were measured, and the results showed that, with the increase of growth temperature,the luminescence intensity of ZnS increased but the luminescence intensity of PS decreased. Combining the blue-green emission from ZnS with the red emission from PS,a broad PL band in the visible region from 450 nm to 700 nm was ob rained,which exhibited intensively white light emission.