Ion behavior near liquid/solid interface in nanowire FET biosensors
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Date
2025
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Abstract
This thesis investigates ion behavior at the liquid/solid interface in nanoscale silicon nanowire (Si NW) field-effect transistor (FET) biosensors. Advanced liquid gate-all-around (LGAA) NW FETs were developed to explore key interfacial effects, including charge inversion, the space-charge-limited-current (SCLC) effect, and random telegraph signal (RTS) phenomena linked to single trap events. Noise spectroscopy revealed two characteristic turning points in Hooge parameter (αH) and equivalent input noise (SU) at MgCl2concentrations of 10⁻⁴ M and 10⁻¹ M, indicating distinct ion behavior transitions. Further studies in PBS demonstrated the SCLC effect, accompanied by RTS in the corresponding I–V range, providing new insights into charge transport and trapping mechanisms. To enhance device sensitivity, a gold bowtie antenna was integrated on the NW surface, enabling optically induced RTS under 940 nm illumination without dielectric breakdown. These results demonstrate that plasmonic enhancement via the antenna effectively amplifies biosensor response, paving the way for next-generation, highly sensitive bioelectronic sensing technologies.
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Gate-all-around, Ion behavior, FET, Noise, Random telegraph signal