脉冲激光沉积ZnSe:Co_(x)纳米晶薄膜的微结构及光学性质研究

Studies on the Microstructure and Optical Properties of Nanocrystalline ZnSe:Co_(x) Thin Film Prepared by Pulsed L aser Deposition

采用脉冲激光沉积技术在基片温度为800℃条件下制备了不同Co含量的ZnSe:Co_(x)(x=0.1,0.3,0.5)微晶薄膜。通过X射线衍射、原子力显微镜、X射线光电子能谱、红外透射光谱及光致发光光谱分析了薄膜的微结构及光学特性。结果表明:所制备的纳米晶薄膜结晶质量优秀,具有(111)择优取向,薄膜结晶质量、光谱透射率和光学带隙均随Co含量的增加而减小;薄膜在波长约700~850 nm处存在一吸收带,这源于Co^(2+)在周围Se^(2-)构成的四面体晶场中^(4)A_(2)(^(4)F)→^(4)T_(1)(4P)能级之间的跃迁;当Co掺入量x=0.5时,薄膜达到过掺杂状态,α-Co杂质相出现,薄膜红外光致发光谱大幅降低。

ZnSe:Co_(x)(x=0.1,0.3,0.5)nanocrystalline thin films were deposited on sapphire substrates by pulsed laser deposition at substrate temperature of 800℃.The crystal structure and optical properties of the thin films were investigated by X-ray diffraction,atomic force microscope,X-ray photoelectron spectroscopy,optical transmittance and photoluminescence spectra.The results show that the thin films with excellent crystalline quality and(111)preferred orientation are prepared.With increasing Co concentration,the crystalline quality,average transmittance and band gap of films decrease.There is a absorption band at the wavelength of about 700-850 nm in the film,which comes from the transition between ^(4)A_(2)(^(4)F)→^(4)T_(1)(4P)energy levels of Co^(2+)in the tetrahedral crystal field composed of surrounding Se^(2-).The films reach an overdoping state when the x value increases to 0.5,and the photoluminescence intensity of films decrease substantially due to theα-Co impurities un-incorporating into ZnSe lattice.