Light enhanced NO2 gas sensing with tin oxide at room temperature: conductance and work function measurements

The NO2 gas sensing behaviour of nano-particular SnO2 is studied at room temperature under illumination. SnO2 samples were sputtered on interdigital contact (IDC) substrates for conductance measurements and Pt-coated Si-substrates for work function potential measurements by Kelvin probe. Moreover, we used spectral filters and attenuation filters to study light induced gas adsorption and desorption mechanisms. Two main effects have been observed: the conductance is increased and the time constant for NO2 desorption is drastically reduced. Furthermore, the gas induced baseline shift has been reduced. The results can be explained with a surface photovoltaic model.