Interface Engineering of Metal‐Oxide Field‐Effect Transistors for Low‐Drift pH Sensing

Abstract Field‐effect transistors (FETs) with nanoscale channels have emerged as excellent platforms for constructing high‐sensitivity biosensors. However, in typical FET‐based biosensors, the electronic perturbation at channel/electrolyte interfaces results in poor stability and severe signal drifts, making long‐term continuous measurements quite challenging. To address this issue, here the dielectric/semiconductor interface is tailored by depositing an ultrathin layer of Al 2 O 3 (≈7 nm in thickness) on In 2 O 3 FETs via solution‐based processes. The results show that the Al 2 O 3 dielectric layers effectively passivate the In 2 O 3 channel and endow the device with low operation voltage (0.05 V), high sensitivity (61.9 mV pH −1 ), and low current drift (0.35 mV h −1 ) upon long‐term and continuous pH monitoring. This work paves the way to real‐time biosensing with high sensitivity, excellent stability, and low power consumption.