Surface-depletion controlled gas sensing of ZnO nanorods grown at room temperature

The authors report on surface-depletion controlled gas sensing ZnO nanorods. These nanorods were synthesized through a simple wet chemical route at room temperature. The diameter of nanorods is about 15 nm, which is close to two times of the Debye length of ZnO. In contrast to the previous report, the sensing is surface-depletion controlled rather than contact controlled and the sensitivity is up to 29.7 against 100 ppm ethanol. Such high sensitivity is due to an almost complete depletion of the rods in air, which is confirmed from photoluminescence spectrum and x-ray photoelectron spectroscopy. The gas sensing mechanism controlled by surface depletion provides another approach to realize high-performance gas sensors. (C) 2007 American Institute of Physics.