化学沉积法制备CdS纳米薄膜及成膜机理

Preparation and Formation Mechanism of CdS Nano-films via Chemical Bath Deposition Technique

分别以Cd(NO3)2和(NH2)2CS作为镉源和硫源,用化学沉积法(CBD)在ITO玻璃上生长CdS半导体纳米薄膜.考察了Cd2+浓度、沉积温度、沉积时间和后处理温度对CdS成膜的影响.紫外-可见吸收谱和原子力显微镜结果表明,改变溶液浓度和后处理温度都能有效调节CdS的吸收带边,得到均一致密的CdS纳米薄膜.探讨了膜形成机理,给出了成核过程模型,进一步修正了传统成膜机制.认为ITO玻璃基片表面活性位和晶核的形成是均一致密CdS纳米膜形成的关键.晶核的形成是电学、热学、力学和化学等因素共同作用的结果.

CdS semiconductor nano-films were grown on ITO glass substrates by means of chemical bath deposition （CBD） technique with Cd（NO3 ）2 asthe Cd ions and （NH2）2CS as the S ions source. The concentration of Cd ions, deposition time and post-treatment temperature have impact on CdS nano-films formation. UV-Vis absorption spectrum and Atomic Force Microscope （AFM） image indicate that the change of concentration of Cd ions and post-treatment temperature may adjust the band-gap of CdS to obtain stable uniform and compact hard films. Formation mechanism of the crystal nucleus and CdS film was also discussed. Active sites on the surface of ITO are critical to the formation of crystal nucleus and uniform compact CdS nano-film. The active site and crystal nucleus are formed due to the comprehensive effect of electricity, thermodynamics and chemistry.