Au/graphene/n-InP Schottky barrier diode (SBD) was fabricated by the use of spray pyrolysis technique with a monolayer graphene interlayer, and the temperature dependent characteristics was performed in a wide temperature range from 60 to 300 K with steps. The Au/GR/n-InP SBD exhibited excellent rectifying behavior however barrier height (Phi(b0)) of the device increased with increasing temperature while ideality factor (n) and series resistance (R-s) decreased. The strong temperature dependency of SBH and the deviation from theoretical value of Richardson constant clarified by considering a Gaussian distribution model of the SBH which was caused by the BH inhomogeneities. The mean BH (Phi) over bar (b0) of 0.94 and 0.59 eV was estimated with the standard deviation of 0.011 and 0.004 eV attributed to the presence of a double GD of SBD. The modified Richardson plots gave mean BH value of 0.98 and 0.70 eV and the Richardson constant values of 8.10, 13,38 A K-2 cm(-2) was very close to its theoretical value of 9.4 A K-2 cm(-2). These results yields that carrier transport mechanism of Au/GR/n-InP SBD can be clarified by Thermionic-emission-diffusion (TED) mechanism with a double Gaussian distribution of the SBHs. In addition, the I-V characteristics of SBD under dark and light ambiance indicates that Au/graphene/n-InP is strongly dependent on the light effect. Thus, we can conclude that graphene/n-InP device is a potential candidate for photovoltaic systems. Moreover, the UV-vis spectroscopy of the graphene film exhibit a strong absorption as A = 9.45% compared to the literature, that is, Au/GR/n-InP SBD grown by spray pyrolysis has excellent optical properties for optoelectronic applications.