Electrical and NOx gas sensing properties of metallophthalocyanine-doped polypyrrole/silicon heterojunctions

Heterojunctions between silicon and polypyrrole (PPy) doped with metal phth alocyanine toluenesulfonate (MPcTS) anions have been studied using current- voltage and capacitance-voltage measurements. The results from current-volt age measurements at different tt temperatures indicated that in the tempera ture range close to room temperature the thermionic emission current is dom inant. These heterojunctions are sensitive to NOx in the ppm concentration range. The electrical and gas sensing properties are strongly influenced by both the PPy characteristics (dopant, film thickness, preparation temperat ure) and the characteristics of the Si substrate (doping type, doping level ). (C) 2001 Elsevier Science B.V. All rights reserved.