CdS纳米晶颗粒薄膜的制备及其光学特性研究

Preparation and Optical Properties of CdS Nano-crystalline Thin Films

采用化学浴沉积法,以CdCl2.H2O、CS(NH2)2、NH4Cl、NH3.H2O和去离子水作为反应前驱物,在不同的氨水浓度下制备CdS纳米晶颗粒薄膜。通过扫描电镜、X射线衍射、X射线能量色散谱、紫外-可见光透射光谱、椭圆偏振光谱等方法,研究了反应前驱物中氨水浓度对CdS纳米晶颗粒薄膜的表面形貌、晶体结构、S/Cd原子比、光透过率、光学带隙、折射率、消光系数和光学吸收边等物理性能的影响。结果表明:反应前驱物中氨水浓度在0.4～1.0mol/L范围内,可以在衬底上形成均匀致密的CdS纳米晶颗粒薄膜。随着氨水浓度的增加,CdS纳米晶的平均晶粒尺寸逐渐减少,S/Cd原子比逐渐增加,由富Cd型转变为富S型,禁带宽度逐渐增加。在500～1000 nm波段内,折射率的平均值为1.75;消光系数k小于0.07。

CdS thin films were prepared by chemical bath deposition （CBD） at different ammonia concentration using CdCl2·H2O、CS（NH2）2、NH4Cl、NH3·H2O and deionized water as precusors. The morphology, structure and S/Cd ratio of all samples were characterized by scanning electron microscopy（SEM）, X-ray diffractionmeter （XRD） and X-ray energy dispersive spectroscopy （EDS）. The optical properties of CdS thin films were studied by using uhravioler-visible spectra and spectra ellipsometry. The results indicate that CdS thin film could be grown when ammonia concentration at the range of 0. 4-1.0 mol/L. With the ammonia concentration increasing, the crystallite size of CdS thin film becomes smaller. The S/Cd atom ratio and band gap gradually increases. Within 500-1000 nm wavelength, the average value of the refractive index is 1.75 and the extinction coefficient is less than 0.07.