A study of hydrogen detection with palladium modified porous silicon Original Research Article

A palladium/porous silicon hydrogen sensor has been developed using for the first time the measurement of contact potential difference variations (CPD). The CPD amplitude and speed of response is shown to depend on the type of silicon substrate, the etching current density used for porous silicon preparation and subsequent oxidation. The temporal response features are compared with a Pd/silicon structure and are discussed in terms of a kinetic equation for adsorbtion–desorbtion reactions. The improvement of CPD response in Pd/porous silicon sensor can be explained by a more developed surface under the Pd coating, by a porous silicon surface covered by hydride species or by creation of a thicker Schottky layer in comparison with Pd/Si contacts.