Surface conductivity measurements by a capacitive coupling technique

We show how the conductivity of a gate-voltage-induced charge layer in a metal-insulator-semiconductor (MIS/MOS) capacitor structure can be measured quantitatively without the need for source-drain contacts. In this scheme, the interface current is driven by an rf voltage applied across a resistive thin-film gate electrode and coupling capacitively to the conducting interface layer. We give examples that illustrate application possibilities and the sensitivity of the technique.