Fast optoelectronic gas sensing with p-type V2O5/WS2/Si heterojunction thin film

The efficiency of ultraviolet (UV) illumination in gas adsorption/desorption is remarkable due to its capacity to activate and energize CO2 molecules, rendering them more reactive and prone to surface interactions. A heterojunction device for room-temperature optoelectronic gas sensing has been fabricated. This was achieved through the deposition of an orthorhombic vanadium pentoxide (V2O5) thin film onto a wafer scale 2D p-type tungsten disulfide (WS2)/silicon (Si). The incorporation of the V2O5 layer brings about alterations in WS2's electronic properties, resulting in increased energy states for photo-generated carriers and a promising approach to enhance the intensity of exciton and trion peaks. Specifically, the WS2 film exhibits a carrier concentration of 3.67 x 1018 cm-3, while incorporating the V2O5 layer significantly raises this concentration to 1.20 x 1020 cm-3. The experiments reveal a rapid response time of 0.4 s and a recovery time of 0.2 s, respectively, demonstrating the swift desorption capability of the device in a CO2 environment. Remarkably, this device exhibits high optoelectronic performances, boasting a detectivity of 1.22 x 1013 Jones and a responsivity of 177.21 A/W. These findings have the potential to advance the development of improved gas-sensing devices, offering heightened sensitivity and selectivity in diverse optoelectronic applications.