Harnessing UV light for enhanced room temperature ultra-low NO sensing via WSe2/GaN heterostructure

Highlight • UV-activated WSe2/GaN heterostructure based room temperature NO gas sensing. • Device exhibits relative sensor response of ∼ 16.8 % (100 ppb NO) and ∼ 92.4 % (10 ppm NO) at RT. • A faster sensing device with response/recovery time of 13.64 sec/21.24 sec. • WSe2/GaN heterostructure-based device can detect extremely low (10 ppb) concentration of NO gas with high selectivity and stability. Transition metal chalcogenides (TMDs) are significant for room-temperature (RT) gas sensing. However, the gas sensing proficiency of WSe2-based sensors is still to be enhanced in terms of selectivity and responsivity. Here, we report UV light-activated WSe2/GaN heterostructure based highly sensitive and selective RT operable NO sensor. The WSe2/GaN device is proficient for NO sensing in a broad concentration range from 100 ppb to 10 ppm. The relative NO sensor response was elevated to 3-fold and 1.75-fold under 266 nm (UVC) and 355 nm (UVA) illumination, respectively. Astonishing relative sensor response of 92.4 % (16.8 %) for 10 ppm (100 ppb) NO gas at RT under UVC is reported with a rapid response/recovery time of 13.64/21.24 sec followed by a significant reduction in the limit of detection (10 ppb). Additionally, impressive sensor responses of 10 % and 58 % were also observed for UVA. Further, the device demonstrates long-term stability and consistent performance with insignificant changes in responsivity, particularly under UVC. Integrating WSe2 with GaN and a large specific surface area boost the charge transfer under UV, leading to superior NO sensing. The device offers significant applications in environmental & healthcare monitoring and provide opportunities for wearable device integration for continuous tracking and monitoring of NO gas.