There have been many attempts on Schottky barrier diodes (SBDs) to improve the quality of metal-semiconductor (MS) structure and control permanently the barrier height (BH) by utilizing an organic or inorganic interfacial layer instead of widely used SiO2. The organic polymer or inorganic insulator interfacial layer insertion to the M/S interface converts the structure into the metal-polymer-semiconductor (MPS) or metal-insulator-semiconductor (MIS). The reliability and performance of the MIS/MPS-type SBDs is drastically affected by the interface layer quality and also its thickness. In this paper, MS structure forms as Au/n-GaAs are consecutively used with an organic interfacial layer polyvinyl alcohol and inorganic interfacial layer zinc oxide to compare their effects on the electrical characteristics of SBDsunder distinct illumination levels. Consequently, the current-voltage characteristics provide us to reveal and compare the improvement and reliabilityof the MPS and MIS-type SBDs by also considering significant electrical parameters, such as ideality factor, apparent BH, and series resistance.