Non-linear dynamic responses of a semiconductor gas sensor: Evaluation of kinetic parameters and competition effect on the sensor response

A novel gas-sensing system based on a dynamic non-linear response is reported. A sinusoidal temperature change is applied to a semiconductor gas sensor, and the resulting conductance of the sensor is analyzed. The sensor response changes characteristically depending on the composition of the gas species and is analyzed by fast Fourier transformation (FFT). Not only the individual concentrations of samples but also the competition effect on the sensor responses to gaseous mixtures are evaluated by the higher harmonics of FFT. The physicochemical parameters on the sensor response are estimated based on information from the non-linear response under the application of temperature modulation. The competition effect on the response to two samples is discussed in relation to the kinetics of gas molecules on the semiconductor surface.