Sensitivity enhancement of ion sensors by charge trapping on Extended Gate Field Effect Transistors

Electrolyte-insulator-semiconductor (EIS) and Extended-gate Field Effect Transistor (EGFET) devices with programmable HfO
2
/Si
3
N
4
/SiO
2
structures are demonstrated for pH detection. The proposed programmable EIS and EGFET sensors with pH sensing membranes exhibit a high pH sensitivity (larger than the ideal Nernstain response, 59.16 mV/pH at 25°C) owing to the hydrogen ions attraction by electrons trapped within the embedded trapping layer(Si
3
N
4
) after programming. When compared with the conventional devices, the programmable sensors with programming provide the possibility for the small pH fluctuation detection and can be used in future pH sensor applications owing to its high pH sensing response.