A Nanoribbon-Based Ion-Gated Lateral Bipolar Amplifier for Ion Sensing

Nanoscale sensors usually produce feeble signals susceptible to inevitable external interference. Several signal amplification solutions exist for mitigating the interference. However, most nanoscale sensors are fabricated on silicon-on-insulator (SOI) substrate, which is not compatible with the integration process of traditional vertical bipolar amplifiers. This work presents an ion-gated lateral bipolar amplifier that integrates a nanoribbon filed-effect transistor (NRFET) ion sensor with a lateral bipolar junction transistor (LBJT), all on an SOI substrate, thereby greatly simplifying the fabrication process. The direct connection between the LBJT base and the NRFET source enables immediate amplification of the NRFET signal, minimizing exposure to surrounding interference. Characterized by a peak current gain exceeding 20, this amplifier design leads to a 3-7-fold enhancement in the overall signal-to-noise ratio (SNR) compared to a reference NRFET. Furthermore, this gain in SNR is empirically validated during pH sensing applications. The possibility of substrate biasing makes the integrated LBJT-NRFET amplifier unique as it can independently tune the current gain and reduce the noise thereby improving the SNR performance.