Electrical and CO gas-sensing properties of ZnO/SnO2 hetero-contact

Stable and reproducible hetero-contact samples of SnO2:3Zn and ZnO:55n were successfully fabricated by co-firing two oxide layers at 800 degrees C for 3 h. Hetero-contact sample showed higher resistivity and sensitivity to 200 ppm CO gas than individual SnO2:3Zn or ZnO:5Sn. The electrical and CO gas-sensing properties of hetero-contact samples were strongly dependent on the sample thickness; the thinner hetero-contact sample showed the higher resistivity and the higher sensitivity to 200 ppm CO gas than the thicker one. In other words, the interfacial element has more distinctive influence on the gas sensitivity. From these results, it is proposed that SnO2(n)/ZnO(n) hetero-contact interface works as a good sensing element. (C) 1999 Elsevier Science S.A. All rights reserved.