*3.1.5 Chemical vapor deposition*

The IO based nanostructured thin films can also be fabricated by CVD [43]. In this process, the combination of gases react with substrate surface at comparatively high temperature that leads to decay of a particular constituent of gas combination. Hence, the fabrication of a metal or composite solid film can be deposited onto a substrate. This process can either be a pyrolysis of vapors of single organometallic compounds or a second reactant as an intermediate in vapor phase [43]. In this regard, some reports are available (**Table 2**) on single-phase metastable rhombohedral ITO epitaxial thin films with high transparency and electrical conductivity. The films had been deposited on Al2O3 substrate by CVD [43]. Also, indium gallium oxide thin film had been developed by co-sputtering using Ga2O3 and In2O3 as targets at room temperature [43].
