Metal-Insulator-Metal Tunneling

Abstract

In principle, it is easy to perform a tunneling experiment. Imagine the simple DC circuit shown in Fig. 1, consisting of two parallel capacitor plates connected to a battery. There are also an ammeter, a voltmeter, and some resistors in the circuit so that we can measure the current through the capacitor and both measure and vary the voltage applied to the capacitor plates. Normally, we do not expect a DC current to flow between the capacitor plates; however, if the capacitor plates are spaced very close together (on the order of 50 Å),we find that a DC current is easily detectable with an ordinary ammeter, and we may get a current—voltage char­acteristic somewhat as shown in Fig. 1. The DC current flowing through the thin insulator between the capacitor plates is a tunneling current.