Since the discovery of the electric-field induced large resistance change, i.e., colossal electroresistance (CER) effect, the CER devices have attracted considerable attentions due to the potential application for the next-generation random access memory. Metal/Nb:SrTiO3 Schottky junction device, which exhibits the bi-polar type resistance switching (RS), is one of promising candidates and numerous investigations have been conducted to understand the CER effects. In spite of making many efforts, even now the RS mechanism is not fully understood, and the improvement of RS properties must be needed because of its poor RS and retention properties. In present study, we fabricated the PtOx/Nb:SrTiO3 junctions under the various partial oxygen pressure and investigated the Schottky barrier height and its contribution to the RS properties. Since the RS of Pt/Nb:SrTiO3 Schottky junctions originate from the change in current conduction through Schottky barrier and Pt is a known oxygen dissociation catalyst, it is expected that the oxidation of Pt electrode should strongly influence the Schottky barrier contact and the RS properties. As a result, we found that the oxidation of Pt electrode strongly enhances and suppresses the RS properties and they originate from the difference of Schottky barrier profiles at the electrode interface by using the photoemission spectroscopic techniques. In my talk, I would like to briefly introduce our company and my research interests and talk about the detailed experimental results and possible mechanism of improvement.