The effect of annealing on the sensing properties of porous silicon gas sensor: Use of screen-printed contacts

A gas sensor utilizing a porous silicon layer and a thick film printing technique, instead of thin film deposition and photolithographic methods for fabricating such a device, is presented. The contact structure consists of a printed silver metal grid on the top of the porous silicon surface and an aluminium ohmic contact at the bottom, which were formed by a screen-printed metallization process. Freshly prepared porous silicon (PS) surfaces have been modified with organic molecules (CHx groups) in a thermal process in order to replace the hydrogen termination by monolayers attached to the surface through Si-C bonds. In this work, we report the experimental results of a porous silicon based sensor whose contacts were treated at different temperatures, ranging from 200 to 750 degrees C, and the effect of this thermal process on the reorganization of the PS bond configuration. (C) 2006 Elsevier B.V. All rights reserved.