Optically Programmable Smart WSe₂/hBN Heterostructure Gas Sensors

Highly sensitive and energy-efficient gas sensors are essential for real-time environmental monitoring and air quality assessment. In this work, we present an optically programmable gas sensor based on WSe₂/hBN heterostructure transistors for NO_x detection. The hBN interfacial layer enhances device performance by reducing charge trapping and improving transport, enabling the WSe₂/hBN configuration to achieve a higher sensing response and faster recovery than WSe₂/SiO₂ devices. To understand the sensing mechanism, in situ Kelvin probe force microscopy (KPFM) was used, revealing that NO_x adsorption at the metal/semiconductor interface modulates the Schottky barrier height (SBH), which governs charge transport and gas sensitivity. Furthermore, we demonstrate that UV-induced charge modulation allows dynamic control of the sensor response, offering a tunable and reversible method for optimizing gas detection. This study highlights the potential of heterostructure engineering and optoelectronic modulation in developing next-generation, low-power, smart gas sensors for environmental monitoring applications.