We present results from a study of resistance switching in silicon-rich silica – ie silicon dioxide containing an excess of silicon. We demonstrate that changes in resistance are the result of field-driven movement of oxygen, and that this can result in large-scale changes in oxide structure and stoichiometry. While resistance switching in oxides has been studied for a number of years as a route to non-volatile electronic memories, the optical response of such systems has remained largely unknown. Here we demonstrate that simple two-terminal MIM devices can be switched between different resistance states using a combination of electrical bias and optical stimulation. This opens up intriguing possibilities for novel classes of sensors.

We also demonstrate neuromorphic behaviour in our devices. Our electrical measurements show that, under the right conditions, the devices can be made to emulate some of the important behaviours of biological neurons – plasticity, for example. Taken together with the light sensitivity of these resistance switches, this opens up further possibilities for the development of light-triggered neural networks for such applications as pattern recognition and image classification.