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A new device has been developed for the detection of low NO(2) concentrations in air. The structure consists of a p(+)-Si substrate, an n-Si epitaxial layer, a thin tunnel SiO(2) layer and a thin SnO(2) sputtered film. Some of the sensors have been catalysed with a thin Al sputtered layer to improve the sensitivity and response rate to NO(2). The electrical I-V characteristics are those of a tunnel diode, which shows a bi-stable (low impedance, high impedance) behaviour. The switch may be accounted for by punchthrough and avalanche multiplication at the n-Si layer. It is found that the switching voltage is an increasing function of the NO(2) concentration, as the work function of the SnO(2) increases with the ionosorption of the electronegative NO(2) molecules. The possibility of detecting NO(2) concentrations as low as 50 ppb in air is demonstrated.

Additional information

Authors: BARBI G B, JRC Ispra (IT);SANTOS BLANCO J, JRC Ispra (IT);BAROFFIO M, JRC Ispra (IT);AGAPITO J, Universidad Complutense, Facultad Físicas, Departamento de Electrónica, Madrid (ES);GUTIÉRREZ F J, CENFA, Laboratorio de Sensores, Madrid (ES)
Bibliographic Reference: Paper presented: Eurosensors VII, Budapest (HU), September 26-29, 1993
Availability: Available from (1) as Paper EN 37801 ORA
Record Number: 199410994 / Last updated on: 1994-11-28
Original language: en
Available languages: en