A MOS capacitor is very similar to a Schottky diode except that a thin layer of silicon dioxide is grown before the metal is evaporated. Since the oxide is an insulator, current cannot flow into the device, and there is no IV curve. However, the metal and semiconductor are still coupled through electric fields and thus the voltage can control the charge density at the silicon surface. One characteristic of a MOS capacitor not found in a Schottky diode is an inversion layer.

Two different oxides are made: thin oxides (50nm or so) for MOS capacitors and transistor gates, and thick oxides (400nm or so) for isolation.

Procedure and Results