Current Coupling Effect in MIS Tunnel Diode with Coupled Open-Gated MIS Structure

Abstract

Coupled current-voltage behaviors were observed in a metal-insulator-semiconductor (MIS) tunnel diode with an open-gated MIS structure coupled nearby. The MIS tunnel diode is an Al/SiO2/Si(p) structure. For thicker oxides (around 3 nm), the saturation currents of the two neighboring MIS tunnel diodes (with several micrometers separation) were found the same even though the device areas were over 45 times different between them. The tunneling current of the Al/SiO2/Si(p) tunnel diode is exponentially dependent on the effective Schottky barrier height of holes, which depends on the oxide voltage determined by the electron concentration at the substrate surface. Also, the tunneling current of the Al/SiO2/Si(p) tunnel diode is mainly flowing along the device perimeter due to the fringing field effect. In short, the electron concentration at the substrate surface at the device edge determines the tunneling current of the Al/SiO2/Si(p) tunnel diode, which is the key mechanism to explain the coupled phenomenon.