Effect of Different Radios of Two Complexes on the Structural and Optical Properties of ZnS Thin Films

ZnS thin films were deposited at three different radios of V(NH3·H2O)/V(N2H4) on glass substrates by chemical bath deposition (CBD) method without stirring the deposition bath during the deposition process. The structural and optical properties were analyzed by X-ray diffraction (XRD) and UV-VIS spectrophotometer. The results showed that ZnS thin film deposited at the radio of V(NH3·H2O)/V(N2H4)=15:15 is higher than that of the other two different solutions. With the radio of V(NH3·H2O)/V(N2H4) decreasing from 15:5 to 15:15, homogenous precipitation of Zn (OH)2easily forms in the bath, but ZnS precipitation first become suppressed and then easily forms in solution. It means that the concentration of OH-ion increases with the volume of N2H4increasing, which accelerates the formation of Zn (OH)2. However, when the volume of N2H4increases to 15mL, relatively high concentration of OH-ion not only accelerates the formation of Zn (OH)2, but also be used to the hydrolysis of thiourea. The average transmissions of all the ZnS films from three different solutions (V(NH3·H2O)/V(N2H4)=15:5, 15:10 and 15:15) are greater than 90% for wavelength values in visible region. The direct band gaps range from 3.80 to 4.0eV. The ZnS film deposited for 2.5h with the radio of V(NH3·H2O)/V(N2H4)=15:15 has the cubic structure only after single deposition.