Capacitance-voltage characteristics of amorphous silicon thin-film transistors

We present the results of experimental and theoretical studies of capacitance-voltage characteristics of amorphous silicon thin-film transistors. The small-signal capacitances are calculated as derivatives of channel charge with respect to terminal voltages. The induced charge is evaluated using the same charge-control model for an amorphous silicon thin-film transistor as we used to calculate the current-voltage characteristics of this device. The calculated dependences of capacitances on bias voltages are in good agreement with our experimental data. The capacitance-voltage model is suitable for incorporation into a circuit simulator and can be used for computer-aided design of a-Si integrated circuits.