Influence of Ti Doping on the Optical and Structural Properties of ZnTiO Thin Films Deposited by Electrodeposition Technique

Thin films of titanium doped zinc oxide (Ti-ZnO) have been successfully deposited on fluorine doped tin oxide (FTO) conductive glass substrate using electrodeposition method to study the effects of Ti doping on ZnO films. Zinc acetate and titanium powder digested with hydrogen fluoride were the starting materials used for Zn, Ti and O ions sources. Volume concentration of Ti ions source was optimized. The electrodeposition setup involved three electrodes system with FTO used as working electrode, platinum rod -counter and Ag/AgCl used as the reference electrodes. The deposited thin films of Ti-ZnO were characterized for their optical and structural properties using Uv-Vis spectrometry and X-ray diffraction technique respectively. The results of the characterizations showed that the optical properties of the films such as transmittance, refractive index, extinction coefficient and bandgap energy were influenced by Ti doping. The transmittance (%) was found to decreased for the film (10 ml Ti/ZnO) deposited at highest Ti concentration in the VIS region but increased to the highest value in the NIR region. The bandgap energy of the deposited thin films was found to decrease with concentration of Ti doping. The obtained values were (2.73 – 3.20 eV) for un-doped ZnO and (2.73 – 3.18 eV), (2.80 - 3.0 eV), 2.81 eV and 2.60 eV for 4ml, 6ml, 8ml and 10ml Ti/ZnO respectively. The X-ray diffraction analysis indicated that the fabricated films have crystalline structures which are also influenced by Ti doping. The crystallite size of the films was found to increase while micro-strain decreased as doping concentration increased which signified improvement in crystal structure for device applications. These obtained results positioned the films for wide range of electronic and opto-electronic device applications including transparent thin film transistors (TTFTs) devices like liquid crystal displays (LCDs), light emitting displays (LEDs), transparent electrode in solar cells etc.