A Low Pressure Gas Ionization Sensor Using Freestanding Gold Nanowires

Freestanding gold nanowires (AuNWs) were grown by electrochemically filling the nanoscale pores of anodic aluminum oxide (AAO) membranes, and removing the membrane selectively. The array of vertically-aligned AuNWs was used at one of the electrodes of a capacitor-like gas ionizing cell, while the counter electrode was a polished silicon wafer coated with aluminum. The field enhancement property of high aspect-ratio AuNWs was employed to reduce the gaseous breakdown voltage (V_b) at room temperature. The device was operated in low-pressure gas to study the effect of AuNWs on pre-breakdown current, and tested in sub-torr argon, where it demonstrated considerable reduction in the breakdown voltage compared to uniform field conditions. The effect of nanowire polarity on V_b and the pre-breakdown discharge current was also studied.