No2 Gas Sensor Based On Graphene Decorated With Ge Quantum Dots

We report a NO2 gas sensor based on germanium quantum dots (GeQDs)/graphene hybrids. Graphene was directly grown on germanium through chemical vapor deposition and the GeQDs were synthesized via molecular beam epitaxy. The samples were characterized by atomic force microscope, Raman spectra, scanning electron microscope, x-ray photoelectron spectroscope and transmission electron microscope with energy dispersive x-ray. By introducing GeQDs on graphene, the gas sensor sensitivity to NO2 was improved substantially. With the optimization of the growth time of GeQDs (600 s), the response sensitivity to 10 ppm NO2 can be as high as 3.88, which is 20 times higher than that of the graphene sensor without GeQDs decoration. In addition, the 600 s GeQDs/graphene hybrid sensor exhibits fast response and recovery rates as well as excellent stability. Our work may provide a new route to produce low-power consumption, portable, and room temperature gas sensor which is amenable to mass production.