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

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 degrees 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.

Automated summary

The research introduces a novel class of pressure sensors utilizing the high pressure sensitivity of electrical conduction through the interface between a metal oxide semiconductor nanocrystallite and graphene formed under O-rich conditions. The study on ZnO/Gr interface attributes the observed pressure sensitivity to the spontaneous formation of a sparse layer of oxygen at the interface, controlling electron conduction under strain. The results are anticipated to aid in understanding and engineering of the piezoresistivity and chemiresistivity in metal oxide-Gr composites.