Influence of various complexing agents on structural, morphological, optical and electrical properties of electrochemically deposited ZnSe thin films

Electrochemical deposition (ECD) of ZnSe thin films from aqueous solution containing ZnSO4 center dot 7H(2)O, SeO2 and different complexing agents at bath maintained at 50 A degrees C were investigated. The voltammetric curves were recorded in order to characterize the electrochemical behavior of Zn2+/SeO2 system with different complexing agent and to apply the appropriate range of potential for ECD. GAXRD studies confirms that as-deposited ZnSe thin films using with different complexing agents belongs to the hexagonal phase with (101) plane as the dominant peak. When EDTA, hydrazine hydrate and triethanolamine as complexing agents used, as-deposited films were shows that peaks due to the hexagonal phase along with hexagonal Se reflection observed. EDAX, AES, FESEM and UV-Visible spectrum were used to examine the compositions, morphologies and band gap of ZnSe thin films deposited on ITO glass substrate. A broad photoluminescence (PL) emission peak has been confirmed by a systematic blue-shift in emission peak due to the formation of nanocrystalline ZnSe thin films. In the Raman spectra, high intensity peak of LO phonon mode is observed at 251 cm(-1) using ammonia, citric acid, ethylenediamine and polyvinyl alcohol as a complexing agents. For EDTA, hydrazine hydrate and triethanolamine as a complexing agents used, the phonon was shifted toward lower frequencies. The conductivity type, resistivity, carrier concentrations and electron mobility were measured for the as-deposited ZnSe thin films. As-deposited ZnSe thin films using all complexing agents have n-type conductivity. Electrochemical impedance spectroscopy (EIS) indicated that the ethylenediamine as a good complexing agent for ZnSe thin film deposition and the films demonstrate a less charge transfer resistance (R-ct is 11 Omega) with excellent conductivity compared to other samples.