Effect of Harmful Gases on the A.C. Conductivity of Tellurium Thin Films

Abstract

Impedance spectra of tellurium films with interdigital platinum electrodes have been investigated in NO2 and H2S gaseous media at room temperature. Analyses of Nyquist complex diagrams allowed evaluating the characteristic frequency, time constant, resistance and capacity of the film in different target gases. It is shown that the spectra of both real and imaginary parts of impedance are strongly influenced by gaseous environment. The gas sensitivity for impedance or its imaginary part depends on frequency, being ~50 % / ppm for nitrogen dioxide and ~ 8 % / ppm for hydrogen sulfide respectively. It is suggested that effect of 2 NO andH S 2 results respectively from "strong" and "weak" chemisorptions of these molecules on the surface and intra grain regions.