Abstract
AbstractNanopore covered microporous silicon conductometric gas sensors have been produced via electrochemical etching and standard microfabrication techniques. Reversible and sensitive gas sensors working at room temperature have been fabricated. Sensing of NH3, NOx and PH3 at or below the ppm level have been achieved. The porous silicon (PS) surface has been modified using selective coatings including electroless tin, gold, nickel and copper solutions to increase the response to NOx, NH3, and PH3 respectively. The diffusion of the analyte species has been investigated in the nanopore and micropore regimes by numerical analysis. Comparing the response time of the hybrid porous sensor surface with numerical diffusion calculations on the pores, it has been observed that Knudsen diffusion time scales dominate the sensor response. A transduction model is proposed based on nanopore limited gas diffusion and the experimental response and recovery data.
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