Mosfet gas sensors with metalloporhyrins as gas sensitive materials

Recently, it has been shown that solid films of metalloporphyrins exhibit a remarkable change in work function when exposed to vapours of volatile compounds. This property can adequately exploited fabricating MOSFET sensors where metalloporphyrins deposited onto the gate may provide the necessary chemical sensitivity to the device. Due to their scarce conductivity, porphyrins cannot be utilised for the transistor gate and some strategy is necessary to provide the transistor of the necessary gate bias voltage. In this paper, preliminary results of an attempt to fabricate porphyrin-FET are reported. In particular it is shown a method to obtain a composite gate where gold provides the bias electrode and the porphyrin gives the chemical sensitivity, Response to methanol is qualitatively in agreement with the behaviour reported for porphyrins based quartz resonator sensors.