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 °C, and the effect of this thermal process on the reorganization of the PS bond configuration.