Piezoresistive effect in amorphous carbon thin films

In this contribution amorphous carbon (a-C) films are integrated as strain gauges in micromachined silicon boss membranes. Sputter deposited a-C films have high hardness and < 2 % hydrogen content in it. The tribological properties of the a-C films are comparable with diamond and can be used for hard coatings. The films have very low resistivity which decreases with the temperature. Current voltage characteristics of a-C/oxide Si shows Ohmic behaviour. Variable range hopping mechanism is dominant at low temperatures and is thermally activated at room temperature and at higher temperatures. Piezoresistive gauge factor are measured in the temperature range 23-50 degrees C.