Studies On The Photoelectric Properties Of Semiconductor Thin Films Prepared By SILAR Method

Cadmium sulfide, zinc sulfide, ruthenium disulfide and (Zn,Cd)S thin films were prepared on glass slides by SILAR(successive ionic layer adsorption and reaction)method. The effects of the technological parameters on the quality of the films were studied. The growth rate and surface morphology of the films with cycle times were characterized. The effect of annealing on crystal structure and resistivity of the films were studied. Also, the growth mechanism of heterogeneous reaction of the thin film and technological were discussed.The films as-deposited are amorphous and compact, the growth rate of CdS film is about 2nm/cycle, ZnS film 3nm/cycle and the size of the particles is increased with the cycle times. The contents of the CdS films are not stoichimometric because of formation of Cd-O bond. High pH value has positive effect on the film preparation, and it can enhance the growth rate. To get sulfide films with high quality, the precursors should have proper concentration while the reaction and washing times range from 15~30 seconds for different precursors. The crystallity of the films were enhanced with the increase of the temperature. The resistivity of CdS is obviously decreased with order of magnitude at 673K. The adsorption effiency of (Zn,Cd)S thin films as-depositesd is increased with the decrease of Zn/Cd mol ratio. The band of the (Zn,Cd)S composite films can be tolerated by control the ratio of the ions in the precursors.The film growth is based on the mechanism of heterogeneous growth. The model of surface protonation and double electrical layer were used to explain it.