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-HfO
₂
using fluorine (F
¹⁹⁺
) ion implantation on Electrolyte-Insulator-Semiconductor (EIS) structure is proposed. To concentrate the F atom within a shallow region on HfO
₂
sensing membrane surface, relatively low implant power and big tilt angle are chosen. With suitable F
¹⁹⁺
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-HfO
₂
films, physics analysis including AFM and XPS are both performed.