Optimization of the Electrodeposition Parameters to Improve the Stoichiometry of In 2 S 3 Films for Solar Applications Using the Taguchi Method

Properties of electrodeposited semiconductor thin films are dependent upon the electrolyte composition, plating time, and temperature as well as the current density and the nature of the substrate. In this study, the influence of the electrodeposition parameters such as deposition voltage, deposition time, composition of solution, and deposition temperature upon the properties of In2S3 films was analyzed by the Taguchi Method. According to Taguchi analysis, the interaction between deposition voltage and deposition time was significant. Deposition voltage had the largest impact upon the stoichiometry of In2S3 films and deposition temperature had the least impact. The stoichiometric ratios between sulfur and indium (S/In: 3/2) obtained from experiments performed with optimized electrodeposition parameters were in agreement with predicted values from the Taguchi Method. The experiments were carried out according to Taguchi orthogonal array L27 () design of experiments (DOE). Approximately 600 nm thick In2S3 films were electrodeposited from an organic bath (ethylene glycol-based) containing indium chloride (InCl3), sodium chloride (NaCl), and sodium thiosulfate (Na2S2O3·5H2O), the latter used as an additional sulfur source along with elemental sulfur (S). An X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDS) unit, and scanning electron microscope (SEM) were, respectively, used to analyze the phases, elemental composition, and morphology of the electrodeposited In2S3 films.

电沉积制备的半导体薄膜的性能，取决于电解液组成、沉积时长、温度，同时也受电流密度与基底性质的影响。本研究采用田口方法（Taguchi Method），分析了电沉积参数——包括沉积电压、沉积时长、溶液组成及沉积温度——对三硫化二铟（In2S3）薄膜性能的影响。田口分析结果表明，沉积电压与沉积时长之间的交互作用具有显著性；沉积电压对三硫化二铟薄膜的化学计量比影响最大，而沉积温度的影响最小。通过优化电沉积参数得到的实验样品中，硫与铟的化学计量比（S/In: 3/2）与田口方法的预测值相符。实验按照田口正交表L27（）的实验设计（DOE，Design of Experiments）方案开展。本次实验以乙二醇基有机镀液为沉积介质，镀液中含有氯化铟（InCl3）、氯化钠（NaCl）与五水合硫代硫酸钠（Na2S2O3·5H2O），其中五水合硫代硫酸钠与单质硫（S）共同作为额外硫源，最终电沉积得到厚度约为600 nm的三硫化二铟薄膜。分别采用X射线衍射仪（XRD）、能量色散X射线能谱仪（EDS）与扫描电子显微镜（SEM），对电沉积得到的三硫化二铟薄膜的物相、元素组成与微观形貌进行表征分析。