Room temperature sensing properties of networked GaN nanowire sensors to hydrogen enhanced by the Ga2Pd5 nanodot functionalization

Multiple-networked GaN nanowires with excellent sensing properties to hydrogen were realized by functionalizing their surfaces with Ga₂Pd₅-related nanodots. Compared to the bare-GaN nanowire sensors, functionalization improved the relative resistance responses by a factor of >50 at H₂ concentrations ranging from 100 to 2000 ppm. At room temperature, the nanodot-functionalized GaN nanowire sensors exhibited a relative resistance response of 34.1% at 100 ppm H₂. Interestingly, a shell layer was transformed mostly into Ga₂Pd₅-phased nanodots, which was confirmed by X-ray diffraction and transmission electron microscopy. The mechanisms responsible for the improvement induced by nanodot functionalization are proposed in terms of the hydrogen spillover effect.