Measuring Charge Transport in an Amorphous Semiconductor Using Charge Sensing

TL;DR

This paper demonstrates a novel charge sensing technique using a nanometer-scale silicon MOSFET to measure charge transport and density of states in hydrogenated amorphous silicon, especially at high resistances.

Contribution

It introduces a charge sensing method for amorphous semiconductors that enables measurement of extremely high resistances and detailed transport properties.

Findings

Charge sensing agrees with direct current measurements at high temperatures.

The technique probes both field effect and dispersive transport.

It allows extraction of the density of states near the Fermi energy.

Abstract

We measure charge transport in hydrogenated amorphous silicon (a-Si:H) using a nanometer scale silicon MOSFET as a charge sensor. This charge detection technique makes possible the measurement of extremely large resistances. At high temperatures, where the a-Si:H resistance is not too large, the charge detection measurement agrees with a direct measurement of current. The device geometry allows us to probe both the field effect and dispersive transport in the a-Si:H using charge sensing and to extract the density of states near the Fermi energy.