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 ∼112 °C for H2 or room temperature for O3. The sensitivity to hydrogen increases sharply with temperature and multiple nanorods contacted at both ends by ohmic electrodes show currents of ∼10-8 A at 200 °C and a differential current change of ∼18% when changing from a pure N2 ambient to 10% H2 in N2. The nanorods are able to detect small concentrations (3%) of O3 in O2, with changes in current of ∼10-7 A at 25 °C. The sensitivity was 21% for O3 at room temperature. The nanorods also show a strong response to above-band-gap illumination with ultraviolet light.