Ultrasensitive Phosphorene-Based Gas Sensors
Junhong Chen, Ph.D., Distinguished Professor of Mechanical Engineering and Materials Science and Engineering
Director of NSF Water Equipment and Policy I/UCRC
Thursday, May 5th
3:30 – 4:00 pm
Two-dimensional (2D) layered materials have attracted significant attention for device applications due to their unique structures and outstanding properties. Here we report on a field-effect transistor (FET) sensor device based on 2D phosphorene nanosheets (PNS). The PNS sensor exhibits an ultrahigh sensitivity to NO2 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 (ppb) at room temperature. First-principles calculations combined with the statistical thermodynamics predict that the adsorption density is ~1015 cm-2 for the 4.8 nm thick PNS when exposed to 20 ppb NO2 at 300 K. Our sensitivity modeling further suggests that the dependence of sensitivity on the PNS thickness is dictated by the band gap for thinner sheets (10 nm).