Impact of Light Excitation on Liquid Gate-All-Around Silicon Nanowire Field-Effect Transistor Biosensors with Bowtie Antenna

Recently it is shown that sensitivity of biosensors can be considerably improved using single trap phenomena resulting in two-level random telegraph signal (RTS) switching in current. To develop the transistor structure with a predefined trap position using gold antenna is suggested, which can be excited by light of different intensities to influence the properties of the underlying dielectric layer. High-quality liquid gate-all-around (LGAA) silicon nanowire (NW) field-effect transistor (FET) biosensors are fabricated with a gold bowtie antenna. The transport and noise properties of these new NW FETs are investigated at 940 nm LED excitation in a 1 mm phosphate-buffered saline (PBS) solution with pH = 7.4. A strong sensitivity of I–V and noise characteristics is revealed with an increase in LED intensity. Well-resolved Lorentzian components are only found under the influence of light excitation. A two-level RTS is successfully excited with linear dependence of its amplitude versus intensity. In addition, repeatable fluctuations in current are resolved as small peaks in I–V curves under infrared illumination, thus confirming the excitation of a two-level RTS in the biosensors. The results demonstrate that the FET devices with a gold antenna have significant potential for the excitation of two-level signals to enhance the sensitivity of biosensors.