COMPARISON OF AC AND DC MEASUREMENT TECHNIQUES USING SEMICONDUCTING GA2O3 SENSORS

Ga2O3 thin films as a new base material for semiconductor gas sensors show stable semiconducting and gas-sensitive properties in a wide operating temperature range between 300 and 1000 degrees C. Due to this big operation temperature range different gas-Ga2O3 interactions and thus different gas sensitivities may be selected by choice of the operation temperature. A.c. and low frequency d.c. measurement techniques were applied to the sensors at different operation temperatures. At 600 degrees C and below significant polarization effects were encountered when using the d.c. technique and the resistances were bigger when compared with the a.c. technique. This is attributed to some ionic conductivity in the Ga2O3 layer. In this case, the a.c. technique has proven to be advantageous, yielding shorter response times and more stable readings. In the temperature range 800-1000 degrees C no difference between the a.c. and d.c. measurements occurs which points to a purely electronic conduction mechanism.