摘要
Deposition and structural characteristics of cadmium sulfide (CdS) thin films by chemical bath deposition (CBD) technique from a bath containing thiourea,cadmium acetate,ammonium acetate and ammonia in an aqueous solution are reported.Researches are made on the influence of the fundamental parameters including pH,temperature,and concentrations of the solution involved in the chemical bath deposition of CdS and titration or dumping of the thiourea solution on the structure characteristic of CdS thin films.The pH of the solution plays a vital role on the characteristic of the CdS thin films.The XRD patterns show that the change in the pH of the solution results in the change in crystal phase from predominant hexagonal phase to predominant cubic phase.The CdS thin films with the two different crystal phases have different influences on CIGS thin film solar cells.The crystal mismatch and the interface state density of the c-CdS(cubic phase CdS) and CIGS are about 1 419% and 8 507×10 12cm -2 respectively,and those of the h-CdS(hexagonal phase CdS) and CIGS are about 32 297% and 2 792×10 12cm -2 respectively.It is necessary for high efficiency CIGS thin film solar cells to deposit the cubic phase CdS thin films.
报道了CdS薄膜的CBD法沉积及其结构特性 ,其中的水浴溶液包括硫脲、乙酸镉、乙酸铵和氨水溶液 .研究了水浴溶液的 pH值、温度、各反应物溶液的浓度和滴定硫脲与倾倒硫脲等基本工艺参数对CdS薄膜结构特性的影响 .其中 ,溶液的pH值对CdS薄膜的特性起着关键的作用 .XRD图显示了随着溶液 pH值的变化 ,薄膜的晶相由六方相向立方相转变 .CdS薄膜的这两种晶相对CIGS薄膜太阳电池性能的影响不相同 .c CdS(立方相的CdS)与CIGS之间的晶格失配和界面态密度分别为 1 4 19%和 8 5 0 7× 10 12 cm-2 ,而h CdS(六方相的CdS)与CIGS之间的晶格失配和界面态密度则分别为 32 2 97%和 2 792× 10 12 cm-2 .高效CIGS薄膜太阳电池需要的是立方相CdS薄膜 .
