Purely electronic insulator-metal transition in rutile VO₂

Volatile resistive switching in neuromorphic computing can be tuned by external stimuli such as temperature or electric-field. However, this type of switching is generally coupled to structural changes, resulting in slower reaction speed and higher energy consumption when incorporated into an electronic device. The vanadium dioxide (VO₂), which has near room temperature metal-insulator transition (MIT), is an archetypical volatile resistive switching system. Here, we demonstrate an isostructural MIT in an ultrathin VO₂ film capped with a photoconductive cadmium sulfide (CdS) layer. Transmission electron microscopy, resistivity experiments, and first-principles calculations show that the hole carriers induced by CdS photovoltaic effect are driving the MIT in rutile VO₂. The insulating-rutile VO₂ phase has been proved and can remain stable for hours. Our finding provides a new approach to produce purely electronically driven MIT in VO₂, and widens its applications in fast-response, low-energy neuromorphic devices.