Gas-sensitive p-GaAs field effect device with catalytic gate

A new gas-sensitive catalytic gate p-channel GaAs field effect device with additional sidegate has been developed. With SnO2 as catalytic gate, the device resembles a JFET. The n-type SnO2 gate forms a hetero pn-junction to the p-type channel. The gas-induced change of the gate to channel electric field affects this junction and thus modulates the conductivity of the channel. Gas measurements were carried out at constant temperature and in temperature pulsed mode with test gases like ammonia, methane, carbon monoxide and nitric dioxide in synthetic air with 50% humidity. SnO2-catalysed GaAs–FETs show NO2 and NH3 sensitivity. The Pd-catalysed device reacts only to NO2. CO and CH4 sensitivity of the device was not observed.