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TIN OXIDE HUMIDITY SENSORS OPERATING AT ROOM TEMPERATURE OBTAINED BY CO-EVAPORATION OF TeO2 AND Sn

B. Georgieva1, I. Podolesheva1,* , J. Pirov1, V. Platikanova1

Affiliation

  1. Central Laboratory of Photoprocesses "Acad. J. Malinowski", Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 109, 1113 Sofia, Bulgaria

Abstract

In this paper the humidity sensing properties of layers, prepared by a new method for obtaining doped tin oxide – the vacuum co-deposition of TeO2 and Sn, are studied. The as deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of oxides of Sn and Te, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio Sn/Te and the evaporation conditions. It is shown that as-deposited layers with Sn/Te-ratio » 0.7 - 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature – very high sensitivity, fast response and a very short recovery period. No hysteresis effects are observed. Accelerated ageing tests have shown that the layers possess a good long-term stability. The influence of a number of parameters (layer composition and thickness, thermal pre-treatment, material of the substrate and electrodes, etc.) is discussed..

Keywords

Tin oxide, Thin layers, Humidity sensors.

Submitted at: Aug. 25, 2005
Accepted at: Sept. 22, 2005

Citation

B. Georgieva, I. Podolesheva, J. Pirov, V. Platikanova, TIN OXIDE HUMIDITY SENSORS OPERATING AT ROOM TEMPERATURE OBTAINED BY CO-EVAPORATION OF TeO2 AND Sn, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 5, pp. 2595-2600 (2005)