Resistive NO2 gas sensor based on GaN hexagonal pits at room temperature

Although fantastic milestones of Gallium nitride (GaN)-based materials in optoelectronic devices had been reached, the focus on the optimization of their geometrical structure for gas-sensing applications was relatively scarce. In this work, we demonstrated NO2 gas sensor based on p-type GaN hexagonal pits (GaN-HP) with high surface-to-volume ratio by wet etching method. The fabricated NO2 gas sensor had high sensitivity, high selectivity, fast response/recovery time. The response of GaN-HP with etching time for 10 min to 2 ppm NO2 gas was 6.2%, which also have quick response and recovery time at room temperature. UV light drastically enhanced the response of GaN-HP sensor by 1.3 times to 100 ppm NO2. The gas sensing mechanism of GaN-HP gas sensor was explored, which provided a theoretical and experimental basis for further research and development of high-performance gas sensors based on GaN material. •A gas sensor based on p-type GaN-HP at room temperature was achieved.•The gas sensor based on p-type GaN-HP has quick response and recovery time.•UV light drastically enhanced the response of p-type GaN-HP sensor by 1.3 times to 100 ppm NO2.