An array of metal oxides nanoscale hetero p-n junctions toward designable and highly-selective gas sensors

Nano-helical array of p-NiO/n-SnO2p-n junctions with well-defined and highly-gas-accessible hetero-interfaces is presented for designable and highly selective gas sensors. The gas sensor having the nanoscale p-n junction sensing layer with a top-and-bottom electrodes configuration was fabricated by conventional photolithography and oblique-angle deposition. The unique device structure enables a predominant modulation in barrier height at the hetero-interfaces, consistent with simulation results, resulting in unusual-yet-promising sensing behaviors upon H2 and NO2 exposure. Based on our experimental and simulation results, and the ability to fabricate a variety combination of metal oxides heterostructures with a reproducible and controllable way, we believe that it becomes possible to design and realize highly-selective sensor array electronic-noses optimized towards target gases on demand.