Channel length dependent sensitivity of Schottky contacted silicon nanowire field-effect transistor sensors

Abstract

In this paper, we examine the dependence of channel length on the sensitivity of Schottky contacted silicon nanowire field-effect transistor sensors. The fabricated experimental devices are used as photosensors as well as chemical sensors for pH sensing. The difference in light illuminated current response depends on the channel length in the linear regime. However, the current ratio (ΔILight-Dark/IDark) shows a different trend, being much improved for a longer channel in the subthreshold regime, which can be explained by the different subthreshold swings. Finally, devices of two different channel lengths are applied to detect the pH value of a solution yielding results similar to photosensing. From these results, we suggest that it is desirable to shorten the channel if the sensor is working in the linear region and increase the channel length if the sensor is used in the subthreshold region.