Highly sensitivity of potassium ion detection realized on fluorinated-HfO2 by fluorine implantation on EIS

In this article, the development of a potassium ion sensor based on the fluorinated-HfO₂ using fluorine (F¹⁹⁺) ion implantation on Electrolyte-Insulator-Semiconductor (EIS) structure is proposed. To concentrate the F atom within a shallow region on HfO₂ sensing membrane surface, relatively low implant power and big tilt angle are chosen. With suitable F¹⁹⁺ implant dosage, the pK sensitivity can be effectively improved from 18.19 to 112 mV/pK, and relatively low drift coefficient of 2.62 mV/h is also achieved in 10 mM potassium electrolyte. To investigate the surface roughness and the fluorine depth profile of the implanted-HfO₂ films, physics analysis including AFM and XPS are both performed.