Negative Capacitance Effect at Interface Between Si Wafers with Undulating Surfaces

The field emission current in a vacuum (IT=αE2/eβ/E, where α and β are constants) depends on the electric field strength E. In other words, the differential resistance (dIT/dV)−1 in a vacuum does not follow Ohm’s law. Therefore, the relationship governing the capacitance and current between two electrodes in a vacuum is an intriguing research topic. In this study, we constructed an interface structure in which contact areas and non-contact vacuum areas coexisted by adhering two Si wafers and measuring the capacitance characteristics of this structure. A volatile capacitance appeared at the interface, with the contact areas contributing to positive capacitance and the vacuum areas contributing to negative capacitance. The tunneling current passing through the interface played an important role in the formation of the negative capacitance.