Pressure Sensitivity of Charge Conduction Through the Interface Between a Metal Oxide Nanocrystallite and Graphene

Abstract Highly sensitive, micron‐size, lightweight, and cost‐effective pressure sensors and pressure sensor arrays are in demand for varieties of sonic, biomedical, tactile, and wearable microelectronic applications. Here, the electrical conduction through the interface between a metal oxide semiconductor nanocrystallite and graphene (Gr) formed in O‐rich conditions is shown to be highly pressure sensitive, and a novel class of pressure sensors operating based on the electronic features of heterointerfaces is introduced. First‐principle studies on ZnO/Gr interface attribute the observed pressure sensitivity to the spontaneous formation of a sparse layer of oxygen at the O‐terminated ZnO/Gr interface. Strained by the external force, this layer controls the electron conduction through the junction. In the reduced oxygen conditions, the formation of a stable and pressure insensitive Zn‐terminated ZnO/Gr junction is predicted, which reversibly transforms to the former upon annealing in air at 300 °C. The presented results concerning the spontaneity of adsorbing oxygen species to the O‐terminated metal oxide/Gr junctions are anticipated to assist understanding and engineering of the piezoresistivity and chemiresistivity in the metal oxide‐Gr composites.