Monolithic Wafer Scale Integration of Silicon Nanoribbon Sensors with CMOS for Lab-on-Chip Application.

Silicon ribbons (SiRi) have been well-established as highly sensitive transducers for biosensing applications thanks to their high surface to volume ratio. However, selective and multiplexed detection of biomarkers remains a challenge. Further, very few attempts have been made to integrate SiRi with complementary-metal-oxide-semiconductor (CMOS) circuits to form a complete lab-on-chip (LOC). Integration of SiRi with CMOS will facilitate real time detection of the output signal and provide a compact small sized LOC. Here, we propose a novel pixel based SiRi device monolithically integrated with CMOS field-effect-transistors (FET) for real-time selective multiplexed detection. The SiRi pixels are fabricated on a silicon-on-insulator wafer using a top-down method. Each pixel houses a control FET, fluid-gate (FG) and SiRi sensor. The pixel is controlled by simultaneously applying frontgate (V) and backgate voltage (V). The liquid potential can be monitored using the FG. We report the transfer characteristics (I-V) of N- and P-type SiRi pixels. Further, the I-V characteristics of the SiRis are studied at different V. The application of V to turn ON the SiRi modulates the subthreshold slope (SS) and threshold voltage (V) of the control FET. Particularly, N-type pixels cannot be turned OFF due to the control NFET operating in the strong inversion regime. This is due to large V (≥25 V) application to turn ON the SiRi sensor. Conversely, the P-type SiRi sensors do not require large V to switch ON. Thus, P-type pixels exhibit excellent I/I ≥ 10⁶, SS of 70⁻80 mV/dec and V of 0.5 V. These promising results will empower the large-scale cost-efficient production of SiRi based LOC sensors.