Hydrogen and ozone gas sensing using multiple ZnO nanorods

ZnO nanorods grown by site-selective molecular beam epitaxy show current - voltage characteristics that are sensitive to the presence of hydrogen or ozone in the measurement ambient for temperatures as low as similar to 112 degrees C for H-2 or room temperature for O-3. The sensitivity to hydrogen increases sharply with temperature and multiple nanorods contacted at both ends by ohmic electrodes show currents of similar to 10(-8) A at 200 degrees C and a differential current change of similar to 18% when changing from a pure N-2 ambient to 10% H-2 in N-2. The nanorods are able to detect small concentrations (3%) of O-3 in O-2, with changes in current of similar to 10(-7) A at 25 degrees C. The sensitivity was 21% for O-3 at room temperature. The nanorods also show a strong response to above-band-gap illumination with ultraviolet light.