Negative Capacitance Effect at the Interface Between Si Wafers with Undulating Surfaces

The field emission current in a vacuum (\(I_{T} = \alpha E^{2}/e^{\beta/E}\), where \(\alpha\) and \(\beta\) are constants) depends on the electric field strength E. In other words, the differential resistance \({(dI_{T}/dV)}^{- 1}\) 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 construct an interface structure in which contact areas and non-contact vacuum areas coexist by adhering two Si wafers and measure the capacitance characteristics of this structure. A volatile capacitance appears 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 plays an important role in the formation of the negative capacitance.