Electrical characteristics of a polyaniline/silicon hybrid field-effect transistor gas sensor

The fabrication of an array of polyaniline/silicon hybrid field-effect transistors is reported. The DC electrical characteristics have been found to be similar to those of conventional enhancement-mode metal-oxide-semiconductor devices. Investigations into the capacitance-voltage characteristics, the temperature dependence of the threshold voltage and the isothermal operating point were undertaken for devices with and without the polymeric material deposited within gaps in the gate electrodes. A delay observed in the response of the drain current on application of a gate voltage is shown to be dependent on both temperature and the presence of certain gases. This effect can be used to detect reversibly nitrogen dioxide at a concentration of 8 parts per million.