ChemFET gas nanosensor arrays with alignment windows for assembly of single nanowires

This work focuses on the fabrication and characterization of Chemical Field-Effect Transistor (ChemFET) gas nanosensor arrays based on single nanowire (SNW). The fabrication processes include micro and nanofabrication techniques enabled by a combination of ultraviolet (UV) and e-beam lithography to build the ChemFET structure. Results show the integration and connection of SNWs across the multiple pairs of nanoelectrodes in the ChemFET by dielectrophoresis process (DEP) thanks to the incorporation of alignment windows (200–300 nm) adapted to the diameter of the NWs. Measurements of the SNW ChemFET array's output and transfer characteristics prove the influence of gate bias on the drain current regulation. Tests upon hydrogen (H₂) and nitrogen dioxide (NO₂) as analyte models of reducing and oxidizing gases show the ChemFET sensing functionality. Moreover, results demonstrate better response characteristics to H₂ when the ChemFET operates in the subthreshold regime. The design concepts and methods proposed for fabricating the SNW-based ChemFET arrays are versatile, reproducible, and most likely adaptable to other systems where SNW arrays are required.