EFFECT OF VARYING pH ON THE OPTICAL AND ELECTRICAL PROPERTIES OF ELECTRODEPOSITED ZnS THIN FILMS.

The effect of varying pH on the optical and electrical properties of electrodeposited ZnS has been studied. The electrical parameter were studied using the Photoelectrochemical (PEC) cell while the optical parameters were studied using the UV-Visible spectrophotometry technique for wavelength range 400 – 1900 nm.  Visual examination revealed that the colour of the ZnS thin films became lighter as the pH reduced. High transmittance, which decreases with increase in the pH were observed at the visible and near infrared regions. The values of the energy bandgaps decreases as the pH values decrease, an indication that the transmittance of the ZnS thin film decreased with decreased pH. The average current density and thickness of the thin films decreased with increasing pH while the thin films were all p-type in electrical conductivity which shows that variation in the pH did not have any significant effect on the conductivity type of the films.

本研究探讨了pH值变化对电沉积硫化锌（electrodeposited ZnS）光学与电学性能的影响。电学性能采用光电化学（PEC）池进行表征，光学性能则通过波长范围为400~1900 nm的紫外-可见分光光度法开展测试。目视观察结果显示，随着pH值降低，硫化锌薄膜的颜色逐渐变浅。在可见光与近红外区域，薄膜透光率较高，且透光率随pH值升高而降低。能带隙数值随pH值降低而减小，这表明硫化锌薄膜的透光率随pH值降低而下降。薄膜的平均电流密度与厚度均随pH值升高而减小；所有薄膜均呈现p型导电特性，说明pH值变化对该薄膜的导电类型无显著影响。