The main focus of this work is the structural and optical characterization of Ga-doped ZnO (GZO) thin film and determination of the device behavior of In/GZO/Si/Al diode. GZO thin films were deposited by RF magnetron sputtering technique from single target. The structural and morphological properties of GZO film were investigated by X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy analysis (EDS) measurements. Optical properties of the film were determined with transmission measurement. Device characterization of In/GZO/Si/Al diode were done with the analysis of temperature dependent current voltage (I-V) measurement. The current conduction mechanism was investigated with the Thermionic Emission (TE) method. The deviation from the pure TE method was observed and this deviation was analyzed under the assumption of Gaussian Distribution (GD) of barrier height (TE emission with GD). The mean standard deviation and zero bias barrier height were calculated as 0.0268 (about %3) and 1.239 eV, respectively. Richardson constant was found to be as 115.42 A/cm(2) K-2 using the modified Richardson plot. In addition, series resistance R-s was obtained using Cheung's function. Finally, the interface state densities D-it were determined by using the forward bias I-V results.