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Characterization of porous poly-silicon as a gas sensor
, Article Sensors and Actuators, B: Chemical ; Volume 100, Issue 3 , 2004 , Pages 341-346 ; 09254005 (ISSN) ; Rahimi, F ; Chavoshi, M ; Ahadian, M. M ; Sharif University of Technology
2004
Abstract
Porous poly-silicon (PPS) is a cheaper alternative to single crystal porous silicon and is a favorable choice for making gas sensors. In this study, porous poly-silicon samples were prepared using different HF concentrations and the structural and gas-sensing properties were studied. The topography of the surface was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The variation of electrical conductivity of the samples in the presence of dry air-diluted acetone, ethanol and methanol showed that for a constant etching current, the sensitivity was highest for samples prepared in 13% HF solution. The structure of the films in the optimum HF...
Characterization of porous poly-silicon impregnated with Pd as a hydrogen sensor
, Article Journal of Physics D: Applied Physics ; Volume 38, Issue 1 , 2005 , Pages 36-40 ; 00223727 (ISSN) ; Iraji Zad, A ; Razi, F ; Sharif University of Technology
2005
Abstract
Porous poly-silicon (PPS) samples, obtained by electrochemical anodization of p-type poly-silicon wafers, were doped with Pd by the electroless process. Rutherford backscattering spectroscopy shows that Pd has diffused a few micrometres into the PPS layer. Scanning electron microscopy and energy dispersive x-ray analysis results demonstrate the presence of Pd as dispersed clusters on the surface. The variation of the electrical resistance in the presence of dry air diluted with hydrogen at room temperature shows that Pd/PPS samples have the ability to sense hydrogen at levels down to several thousands of ppm. This value is far below the flammability limit of hydrogen gas. It was found that...