在多孔硅衬底上制备的ZnS薄膜及其光学性能

ZnS Thin Film Prepared on Porous Si Substrate and Its Optical Properties

用脉冲激光沉积(PLD)方法在多孔硅(PS)衬底上沉积了ZnS薄膜。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、荧光分光光度计分别研究了ZnS薄膜的晶体结构、表面形貌及光学性能。结果表明,ZnS薄膜呈立方相晶体结构,沿β-ZnS(111)晶向择优取向生长;经过300℃真空退火30min后,ZnS薄膜的XRD衍射峰强度增大,表面变得粗糙,在可见光区的平均透射率达到80%以上,适合作太阳能电池过渡层、红外增透膜、红外窗口和头罩等。在退火后的ZnS/PS复合膜体系的光致发光谱(PL)中,除了高能端ZnS的蓝光发射和低能端PS的红光发射外,在光谱中间550nm附近出现了一个新的绿光发射,这归因于ZnS薄膜退火过程中形成的缺陷能级而产生的缺陷中心发光。根据三基色叠加的原理将ZnS的蓝、绿光与PS的红光叠加在一起后,ZnS/PS复合膜体系呈现出了较强的白光发射,这为固态白光发射器件的实现开辟了一条新的捷径。

The ZnS thin film is deposited on a porous Si substrate by using a pulsed laser deposition method. The crystalline structure, surface morphology and optical properties of the ZnS thin film are studied respectively by using a X-ray diffraction instrument, a scanning electron microscopy and a fluo- rescence spectrophotometer. The results show that the ZnS film has a crystalline structure in cubic phase and is grown in a prefered orientation along the 13ZnS （111） direction. After annealing in vacuum at 300 %2 for 30min, the X-ray diffraction peak intensity of the ZnS film is increased and its surface becomes rough. In the visible spectral region, the film has an average transmittance of 80＆So,it is suitable for the buffer layer of solar cells, infrared antireflection coating, infrared windows and domes etc.. In the photoluminescence spectra of the annealed ZnS/porous Si composite system, besides the blue light emission of the ZnS film at the high energy end and the red light emission of the porous Si at the low energy end, there appears a new green light emission at about 550nm. This is attributed to the defectcenter luminescence generated by the defect energy level formed in the annealing process of the ZnS film. According to the tricolor overlay principle, the blue and green light of the ZnS is combined with the red light of the porous Si. As a result, more intensive white light is generated from the ZnS/porous Si composite system. This opens a new way for the realization of solid white light emitted devices.