Ultrahigh sensitivity and layer-dependent sensing performance of phosphorene-based gas sensors

TLDR

Two‑dimensional layered materials are of interest for device applications due to their unique structures and outstanding properties, and this study examines phosphorene sensors at room temperature. A field‑effect transistor sensor was fabricated using two‑dimensional phosphorene nanosheets. The phosphorene FET sensor exhibits ultrahigh NO₂ sensitivity in dry air, reaching a 190 % response at 20 ppb for 4.8‑nm‑thick sheets, with first‑principles calculations predicting an adsorption density of ~10¹⁵ cm⁻² and linking sensitivity to band‑gap effects in thin sheets and effective thickness in thicker ones.

Abstract

Abstract Two-dimensional (2D) layered materials have attracted significant attention for device applications because of their unique structures and outstanding properties. Here, a field-effect transistor (FET) sensor device is fabricated based on 2D phosphorene nanosheets (PNSs). The PNS sensor exhibits an ultrahigh sensitivity to NO 2 in dry air and the sensitivity is dependent on its thickness. A maximum response is observed for 4.8-nm-thick PNS, with a sensitivity up to 190% at 20 parts per billion (p.p.b.) at room temperature. First-principles calculations combined with the statistical thermodynamics modelling predict that the adsorption density is ∼10 15 cm −2 for the 4.8-nm-thick PNS when exposed to 20 p.p.b. NO 2 at 300 K. Our sensitivity modelling further suggests that the dependence of sensitivity on the PNS thickness is dictated by the band gap for thinner sheets (<10 nm) and by the effective thickness on gas adsorption for thicker sheets (>10 nm).