Double target co-sputtering preparation of Sb doped GaN film for room temperature detection of NO2 in darkness

In this work, we present a room temperature (RT, 25 ± 3 °C) nitrogen dioxide (NO 2 ) sensor based on antimony doped gallium nitride (Sb-GaN) thin film, fabricated using a multi-target co-sputtering method with a physical vapor deposition (PVD). The effects of Sb incorporation and sputtering power on gas-sensitive properties of the fabricated sensor were investigated. Intriguingly, the optimized Sb-GaN thin film demonstrated a substantial response ( S = 5.8) to 10 ppm NO 2 gas at 25 °C in darkness, with response/recovery times of 185/750 s and a detection limit (DL) as low as 1.64 ppb. Additionally, the sensor exhibited excellent selectivity, reproducibility and good stability in high humidity environment. The XPS study showed that the sensor’s stability deteriorates in 10 days due to the residual adsorption of oxygen ions on the film’s surface. In addition, the sensor’s response-recovery characteristics under six different light irradiations were compared, and red light was found to significantly accelerate the recovery process of the device. The sensing enhancement (4.5 times) of the Sb-GaN sensor is ascribed to the structure induced by Sb-doping and the augmented active sites. Importantly, these investigations offer a valuable reference for synthesis of reliable, eco-friendly, and energy-efficient sensing materials for gas detection in darkness.