Porous silicon (PS) conductometric gas sensors can exhibit large sensitivity to gases, due to the large surface versus volume ratio of porous silicon. A possible application is the detection of traces of nitrogen dioxide (NO2), an air pollutant. ΔG/G signals in excess of 10 in the presence of concentrations as low as 50ppb in dry air can be demonstrated. Unfortunately, such high sensitivity to NO2 is achieved, in fresh samples, with poor reversibility. Another problem is the interference of water vapor, which also affects the porous silicon conductivity. However, we show that reversibility is complete in aged samples, and sensitivity to water vapor is lowered. Although in aged samples large ΔG/G signals are harder to achieve, we show that concentration levels of NO2 at few tens of ppb are still detectable. © 2003 Elsevier B.V. All rights reserved.
Improved reversibility in aged porous silicon NO2 sensors
OTON NIETO, CLAUDIO JOSE;
2004-01-01
Abstract
Porous silicon (PS) conductometric gas sensors can exhibit large sensitivity to gases, due to the large surface versus volume ratio of porous silicon. A possible application is the detection of traces of nitrogen dioxide (NO2), an air pollutant. ΔG/G signals in excess of 10 in the presence of concentrations as low as 50ppb in dry air can be demonstrated. Unfortunately, such high sensitivity to NO2 is achieved, in fresh samples, with poor reversibility. Another problem is the interference of water vapor, which also affects the porous silicon conductivity. However, we show that reversibility is complete in aged samples, and sensitivity to water vapor is lowered. Although in aged samples large ΔG/G signals are harder to achieve, we show that concentration levels of NO2 at few tens of ppb are still detectable. © 2003 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
