The photofield effect in a-Si: H thin film MOS transistors Theory and measurement

Photofield-effect measurements have been carried out on hydrogenated amorphous silicon metal-oxide-semiconductor (MOS) thin film transistors. An expression for the photocurrent as a function of the gate voltage has been derived, and the experimental results are in good agreement with this expression. The densities of the donor and acceptor states at mid-gap are estimated with the help of the model. A method for determining the width of the band gap is also suggested.