A STUDY OF HYDROGEN DETECTION WITH PALLADIUM MODIFIED POROUS SILICON

A palladium/porous silicon hydrogen sensor has been developed using fo r the first time the measurement of contact potential difference varia tions (CPD). The CPD amplitude and speed of response is shown to depen d on the type of silicon substrate, the etching current density used f or porous silicon preparation and subsequent oxidation. The temporal r esponse features are compared with a Pd/silicon structure and are disc ussed in terms of a kinetic equation for adsorbtion-desorbtion reactio ns. The improvement of CPD response in Pd/porous silicon sensor can be explained by a more developed surface under the Pd coating, by a poro us silicon surface covered by hydride species or by creation of a thic ker Schottky layer in comparison with Pd/Si contacts. (C) 1998 Elsevie r Science B.V. All rights reserved.