2020/09/23 by Sushovan Dhara, Dhara, Sushovan, Himani Jawa +7
Engineering · Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Applied Physics (physics.app-ph) #FOS: Physical sciences #Gas Sensing Nanomaterials and Sensors #Transition Metal Oxide Nanomaterials #physics.app-ph
paper · pdf · doi:10.48550/arxiv.2009.11350
Manuscript 22 pages, 7 figures: SI 12 pages, 11 figures
arxiv created 2020/09/23 · openalex publication_date 2020/09/23 · arxiv updated 2020/09/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Gas sensors built using two-dimensional (2D) MoS2 have conventionally relied on a change in field-effect-transistor (FET) channel resistance or a change in Schottky contact/pn homojunction barrier. This report demonstrates, for the first time, an NO2 gas sensor that leverages a gate tunable type II WSe2 (p)/MoS2 (n) heterojunction to realize a 4x enhancement in sensitivity, 8x lower limit of detection and improved dynamic response when compared to an MoS2 FET sensor on the same flake. Comprehensive sensing measurements over a range of analyte concentrations, gate biases and MoS2 flake thicknesses indicate a novel two-fold electrical response to NO2 exposure underlying the enhanced sensitivity of the heterojunction- (i) a series resistance change that leads to an exponential change in thermionic current at high bias, and, (ii) a carrier concentration change that leads to a linear change in interlayer recombination current near zero bias. The heterojunction diode also exhibits fast and tunable recovery under negative gate biasing. All-electrical (gate controlled) sensing and recovery operation at room temperature makes this a simple, low-overhead sensor. The ability to sense tri-nitro toluene (TNT) molecules down to a concentration of 80PPB highlights its potential as a comprehensive chemical sensing platform.