This paper studies the effect of ultraviolet (UV) light exposure on the resistive switching characteristics of an ITO/HfOx/TiN structure. Unstable and unreliable switching properties are generally observed on the ITO/HfOx/TiN sample. Under the appropriate exposure time, the samples were able to achieve the superior electrical characteristics and reduced resistance dispersion. We suggest that the improvement of switching characteristics and resistance dispersion is related to the oxygen-rich HfO2 layer formed at the M/O interface caused by UV light. This indicates that UV laser exposure is a critical issue in the electrical characteristics of RRAM devices. (C) 2010 Elsevier B.V. All rights reserved.