Enhanced Field Ionization Current Enabled by Gold Induced Surface States to Silicon Nanowires

The employment of nanosized materials has gained much interest for the fabrication of field ionization gas sensors (FIGS) since they have many advantageous properties such as low cost, high sensitivity and high selectivity. In this work, we introduce a physical gas sensor using Si Nanowires (NW) configured as anode. These NWs are synthesized by using electroless etching (EE) technique, a cost effective and scaleable process for vertically aligned Si NWs. A thin layer of gold (Au) coating is subsequently applied to improve the field ionization current by introducing unoccupied local states. Characterization of pristine Si NWs and Au doped Si NWs in terms of current and voltage is done under NH3 and O-2 gases. Our structures show more than five orders of magnitude enhanced field ionization current due to unoccupied local states formed by Au doping.