Humidity sensor based on Ga2O3 nanorods doped with Na+ and K+ from GaN powder

Gallium oxide (Ga2O3) nanorods were prepared from commercial gallium nitride (GaN) powder via the simple thermal annealing method by one step, and they were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDS). The thick film humidity sensors were prepared by spin-coating the sensing materials on Al2O3 ceramic substrates coated with Ag-Pd interdigitated electrodes and the humidity sensing properties were studied in detail. The as-prepared Ga2O3 nanorods are of diameters 40-100 nm and lengths 1-6 mu m, and they are doped with Na+ and K+, successfully. The impedance variation of Ga2O3 nanorods sensor with the humility exhibits good linearity response about four orders of magnitude, when the relative humility (RH) is changed from 11% to 95% at 100 Hz. Response and recovery times are about 6 s and 21 s and the maximum hysteresis is only 3% RH at 100 Hz. The good humility sensing properties may be attributed to the synergistic effect of Ga2O3 nanorods and the ions doping. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.