Nanopatterned polycrystalline ZnO for room temperature gas sensing

We demonstrate that the soft e-beam lithography (soft-eBL) fabricated polycrystalline ZnO nanolines show reproducible response to ppm-level H2 and NO2 even at room temperature, due to the intrinsic Joule heating effect in such nanodevices. The Joule heating effect is confirmed by studying the resistance–temperature relationship of the sensor as well as the persistent photoconductivity phenomena in ZnO. We note that Joule heating increases the nanoline temperature to around 72 °C, which enhances the oxidation–reduction reaction at the ZnO surface. Therefore, the nanolines show faster photoresponse than the thin film. These results may help tailor and optimize gas sensor devices for improved performance.