Capacitance properties of MIS tunnel diodes

The theoretical capacitance properties of the metal-insulator-semiconductor (MIS) tunnel diode are described. It is shown that devices with relatively thick insulating layers display properties similar to conventional MIS capacitors, while those with thinner insulating layers differ appreciably. Frequency-dependent features can occur in the characteristics of these devices as a result of a delayed inversion layer response. The presence of such features in experimental devices provides support for the inversion layer clamping process predicted theoretically. Because of these frequency-dependent features, it is shown that caution must be exercised when using MIS tunnel diodes for obtaining surface-state information.