Light stimulation enhanced detection of NO at ppb-level at room temperature using MoS2/WSe2/GaN heterostructure sensor†

Abstract

With rapid technological advancement, there is a strong demand for developing efficient and precise gas sensing systems for monitoring toxic gases such as nitrogen oxides and ubiquitous pollutants from industrial and vehicular emissions. Conventional high-temperature-operated gas sensors always have disadvantages, such as high power consumption and even damage to the sensing materials. The present study focuses on the enhanced performance of room temperature gas sensors using light as a stimulus in the sensing mechanism. Recent advances in materials science, nanotechnology, and device engineering have advanced gas-sensitive technology based on TMDCs and wide-bandgap semiconductors. The present study focuses on the fabrication of a molybdenum disulfide (MoS₂)/tungsten diselenide (WSe₂)/gallium nitride (GaN) heterostructure for enhanced NO detection. The performance was characterized by measuring its resistance to exposure to various NO concentrations under different light illuminations. The performance of the MoS₂/WSe₂/GaN sensor was more pronounced than that of the previously tested WSe₂/GaN and MoS₂/WSe₂ sensors. Notably, upon illumination under ultraviolet light, its sensor performance increased with higher photocurrent and faster response time. Concretely, at an excitation wavelength of 266 nm, a maximum relative sensor response of ∼130% was achieved with a lower detection limit of 8 ppb and better response and recovery times of 8.56/12.82 s. The test results indicate the sensor's strong selectivity to NO gas along with long-term stability and repeatability. Therefore, these results show intriguing potential for real-time environmental monitoring and industrial safety by exploiting the unique properties of materials for high sensitivity, faster response, and endurance in the MoS₂/WSe₂/GaN heterostructure.