Effect of silicon nanowire etching on signalto-noise ratio of SiNW FETs for (bio)sensor applications

A high signal-to-noise ratio in silicon nanowire (SiNW) field effect transistors (FET) is crucial for detecting low concentrations of biological material as the signal changes are often small and difficult to be differentiated from the baseline signal. This reported work studies the low-frequency noise (1/f ) as in Hooge's constant, alpha sub( H), and the device detection limit of the SiNW FETs to evaluate the influence of the etching process used to define the nanowires (NWs). The extracted average Hooge's constant for wet etching is found to be at least an order of magnitude lower ( alpha sub( H, avg) = 7.96 x 10 super( -4)) compared with dry plasmaetched devices ( sub( H, avg) = 4.1 x 10 super( -2)), indicating a lower surface roughness and/or a lower amount of surface defects. This study shows that the newly developed method improves the electrical properties of the device, making it an interesting alternative to standard approaches used for fabrication of SiNW FETs as (bio)sensors.