Transparent Conducting Oxides (TCOs) are unusual materials as they have to possess a high electrical conductivity with good transparency in the visible region of electromagnetic spectrum. TCOs have many applica¬tions such as electrical inter-connections for window electrodes in flat panel displays, electro-optical devices and solar cells. TCOs are also receiving much attention and recognition as they are promising candidate for optoelectronic application in the ultraviolet to visible range. Other important parameters that determine the usefulness of TCOs are environmental stability, process¬ing compatibility with other device elements and production cost etc. Indium (In) doped tin oxide also known as ITO is used as TCO in industries. Now a days, TCOs have already been largely investigated. Therefore, in the recent years, this has stimulated the development of new TCO materials like doped ZnO.