New Approach for Enhancing Sensitivity in Liquid-Gated Nanowire FET Biosensors Under Optical Excitation

The results obtained for liquid-gated (LG) nanowire (NW) field-effect transistor (FET) sensors analyzed in divalent ion (MgCl2) solutions, which play a crucial role in the human body, are reported. Liquid-gated NW FET sensors fabricated in-house are investigated using I-V characteristics and noise spectroscopy in a wide range of voltages and different intensities of optical infrared irradiation. A new effect is revealed under the influence of external optical excitation. The effect allows for the control of characteristic times of single-trap phenomena: capture time to a single trap, emission time from the trap, and its ratio represented by the dimensionless ratio parameter (R-factor). These parameters enabled an improvement in sensor sensitivity. The findings open prospects for controlling charge states in LG NW FET structures to optimize new parameters for achieving ultrahigh sensitivity in biosensors. The new approach for enhancing biosensitivity in liquid-gated (LG) nanowire (NW) field effect transistor (FET) biosensors is suggested based on the revealed optical effect. Results of studies on drain current fluctuations in LG NW FET structures demonstrate that characteristic times (capture and emission) as well as their ratio, which are parameters reflecting the sensitivity of biosensors, can be fine-tuned by infrared light using light-emitting diode (LED).image