Silicon nanowire field-effect transistor biosensors with bowtie antenna

In this study, we fabricated high-quality, liquid gate-all-around silicon nanowire (NW) field-effect transistor (FET) biosensors with a gold bowtie antenna using a silicon-on-insulator (SOI) wafer. The electrical and noise properties of these novel NW FETs were investigated under 940 nm light-emitting diode (LED) optical excitation in different solutions. A two-level signal (TLS) that is useful for biosensing was successfully activated at the light excitation only. The detection of repeatable fluctuations in current, manifested as minor peaks in the I–V curves under infrared illumination, confirms the activation of a TLS in the biosensors. The TLS demonstrates a linear dependence of its amplitude in relation to intensity. Moreover, we performed TLS studies in MgCl₂ solutions of different concentrations. The results indicate that the FET devices incorporating a gold antenna have considerable potential for the excitation of TLS, thus allowing the sensitivity of the biosensors to be about 300 % enhanced.