Nanocrystalline Silicon EGFET Fabricated via R-ALILE Process for pH Sensing

This study presents the fabrication of a nanocrystalline silicon (nc-Si) extended gate field-effect transistor (EGFET) pH sensor using the reverse aluminum-induced layer exchange (R-ALILE) process. By optimizing the annealing temperature to 650 °C, a well-crystallized nc-Si layer was achieved, resulting in enhanced sensing performance. The fabricated sensor exhibits a voltage sensitivity of 30.9 mV pH −1 and excellent linearity of 99.5% over a broad pH range of 2–12. Furthermore, the sensor demonstrates a low hysteresis of 17.4 mV and a long-term drift as low as 1.32 mV h −1 (mV/h), indicating superior stability and repeatability.