(Invited) Metal Oxide Decorated Porous Silicon Interfaces for Sensor Applications: The Question of Water Interaction, Stability, Platform Diversity, Sensitivity, and Selectivity

Abstract

Key parameters of a metal oxide nanostructure modified porous silicon (PSi) interface affecting the performance of PSi-based sensors are considered are considered. Metal oxide (MOx, MxO, x≥1) nanostructured island sites are deposited to reproducible micron sized p and n-type silicon pores (0.7–1.5 µ-diameter) that facilitate rapid “Fickian” analyte diffusion to these highly active sites, enhancing sensitivity and selectivity. Varying site -analyte sensitivities are predicted by the Inverse Hard/Soft-Acid/Base (IHSAB) model. Nitrogen functionalization converts the decorating metal oxides and an oxidized PSi interface from hydrophilic to hydrophobic character. The micron sized pore structure and nitration decrease water interaction providing enhanced stability. Selectivity in the measurement of multiple gases is possible with a combination of nanostructure based detection matrices, p and n-type charge carrier variation, time dependent diffusion response, and pore structure influenced sensitivity. Pulsed FFT techniques can be utilized to facilitate higher analyte selectivity, and false positive assessment.