High-performance methanol sensor based on GaN nanostructures grown on silicon nanoporous pillar array

GaN/Si nanoheterostructures were prepared by depositing GaN nanograins on silicon nanoporous pillar array (Si-NPA) with chemical vapor deposition method. Structural characterization elucidated that the GaN films composed of massive GaN nanocone-strings/nanowires coating on Si-NPA uniformly. Sensor device with ITO/GaN/Si-NPA/sc-Si structures was further constructed by depositing ITO interdigital electrode. Under the optimum temperature of 350 °C, the GaN/Si-NPA gas sensor demonstrated good sensing responses (Ra/Rg) of 1.22 and 1.92-5 ppm, 200 ppm methanol, respectively. The response and recovery rates to 500 ppm methanol were 8s and 7s, respectively. Such good sensing performances originated from the specific structure feature of GaN/Si-NPA nanostructure sensor, high specific surface area and large surface active sites. Moreover, the sensing mechanisms of the resulting GaN/Si-NPA nanostructure sensor were studied by drawing the methanol adsorption and desorption models based on the n-GaN/p-Si heterojunction. Our results obtained here showed that GaN/Si-NPA heterostructure might be a promising sensing candidate for detecting methanol.