Edge-Topological Regulation for in Situ Fabrication of Bridging Nanosensors

In situ fabrication of well-defined bridging nanostructures is an interesting and unique approach to three-dimensionally design nanosensor structures, which are hardly attainable by other methods. Here, we demonstrate the significant effect of edge-topological regulation on in situ fabrication of ZnO bridging nanosensors. When employing seed layers with a sharp edge, which is a well-defined structure in conventional lithography, the bridging angles and electrical resistances between two opposing electrodes were randomly distributed. The stochastic nature of bridging growth direction at the sharp edges inherently causes such unintentional variation of structural and electrical properties. We propose an edgeless seed layer structure using a two-layers resist method to solve the above uncontrollability of bridging nanosensors. Such bridging nanosensors not only substantially improved the uniformity of structural and electrical properties between two opposing electrodes but also significantly enhanced the sensing responses for NO₂ with the smaller variance and the lower limit of detection via in situ controlled electrical contacts.