NO gas-sensing characteristics of copper phthalocyanine film prepared by plasma-activated evaporation

Abstract

An NO gas sensor that has good mechanical properties and chemical resistance has been fabricated using a CuPc film deposited by r.f. plasma-activated evaporation. As the deposition pressure increases, the film forms a denser structure with reduced grain size and the metal-ligand (Cu-N) bonds are greatly deformed by the r.f. plasma. The sensitivity, represented by the relative resistance change, is higher for the sensor prepared at lower deposition pressures because the CuPc films deposited at lower pressures are more porous and hence allow more NO gas molecules to be adsorbed. As the sensing temperature increases, the sensitivity is degraded because the adsorption is an exothermic process. The sensitivity increases almost linearly with the NO gas concentration up to 80 ppm, above which it is saturated to 0.94. The CuPc NO sensor shows good gas selectivity for NO against CO gas and stable reproducibility with desorption treatment.