Pristine SiNW Thin-Film Gas Sensors: Poole-Frenkel Transport-Enabled H₂S Detection

We report a two-terminal gas sensor based on gold nanoparticle (AuNP)-decorated silicon nanowire (SiNW) thin films for selective detection of hydrogen sulfide (H₂S), a toxic gas of environmental concern. FESEM and optical profilometry confirm clustered nanowire films with ∼10 nm AuNPs serving as catalytic adsorption sites. Electrical characterization reveals nonlinear Poole-Frenkel transport in intrinsic SiNW thin films, with slow annealing producing uniform networks and nearly an order of magnitude higher current than rapid annealing. Gas sensing measurements show concentration-dependent responses from 1-10 ppm H₂S, with slow-annealed AuNP-SiNW devices achieving a maximum sensor response of ∼171 % at 10 ppm. Selectivity tests demonstrate strong discrimination against SO₂, NO₂, NO, CO₂, and NH₃, owing to the high sulfur-gold affinity. These results highlight AuNP-SiNW thin films as a compact, low-power platform for real-time H₂S monitoring in environmental and climate safety applications.