Effect of Non-Catalytic and Catalytic Electrode Contacts on Pd Modified Porous Silicon for Hydrogen Sensing

Porous silicon (PS) was prepared from p-type (2-5 Omega cm resistivity) crystalline silicon by electrochemical anodization method using HF and ethanol as electrolyte. To passivate the surface and interface states of porous silicon and to stabilize its property PS surface was modified using PdCl2 by chemical dipping method. Non-catalytic (Al) and catalytic (Pd-Ag) metals were deposited on the samples for two different structures e.g., Al/PS/Si/Al and Pd-Ag/PS/Si/Al both for unmodified and Pd modified porous silicon surfaces. All these sensors were used to study the response for hydrogen in details at room temperature. Compared to the Al/PS/Si/Al structure the response is higher and the time of response and recovery is faster in case of Pd-Ag/PS/Si/Al sensors both for unmodified and Pd-modified PS. Stability of these sensors were also investigated and it was found that Pd modified sensors were very stable and showed more consistent performance.