光快速热处理对化学水浴法合成的ZnS薄膜的微结构和光学性质的影响

Effects of Rapid Thermal Treatment on the Microstructure and Optical Properties of ZnS Films Synthesized by Chemical Bath Deposition Method

采用化学水浴法,以乙酸锌、硫脲、氨水和去离子水为反应前驱物制备了Zn S薄膜.采用SEM、XRD、紫外-可见吸收光谱和荧光光谱研究了光快速热处理温度(Trtt)对Zn S薄膜的表面形貌、结晶和光学性能的影响,同时对Zn S薄膜的形成机理做了分析.研究结果表明:光快速热处理前后,Zn S薄膜均基本呈非晶态,这显示仅采用氨水做络合剂并不能在硅(100)衬底上制备结晶的Zn S薄膜;随着Trtt的升高,Zn S薄膜的吸收边趋于红移,该红移可归结于薄膜应力的变化;在250 nm的紫外光激发下,as-depo的Zn S薄膜在470 nm附近出现的宽峰可归结于Zn S薄膜表面硫的不饱和sp3轨道引起的空穴陷阱和Zn空位的缺陷.Trtt的升高起初增加了薄膜中的点缺陷,随后由于薄膜内部的原子重新排列导致点缺陷减少.薄膜中的点缺陷含量与可见光区的发光强度成正比.

ZnS films were synthesized by chemical bath deposition with zinc sulfate,thiourea,ammonia liquor and de-ionized water as precursors. The effects of the rapid thermal treatment temperature（ Trtt）on the morphology,crystallization,and optical properties of the ZnS films before and after the rapid thermal treatment were investigated by using scanning electron microscopy,X-ray diffraction,UV-Vis spectrophotometer and fluorescence spectral analysis. Furthermore,the formation mechanism of the ZnS film was analyzed. The results showed that the ZnS films before and after the rapid thermal treatment were amorphous,which indicated that it was impossible to synthesize the crystalline ZnS film on the Si（ 100）substrate only using ammonia liquor as complexing agent; the absorption edge of the film tended to red shift with Trtt,which was attributed to the change in the film stress; and the wide photoluminescence peak centred at 470 nm of the as-depo ZnS film was caused by the existing point defects,i. e.,void trap and Znvoids arising from the deficiency of the sulfur on the film surface. The increase in Trttinitially increased the content of point defects,and then reduced the content of point defects because of the rearrangement of internal atoms. The content of point defects was in proportion to the strength of photoluminescence peak in the visible region.