A Scalable Method for Quantifying Ion Transport in Dielectrics

Abstract

The ability to quantify ion transport in a dielectric is of major interest for the development of reliable biomedical devices. A novel and scalable method for accomplishing this is established in this thesis. As ions from the gate of an electrolyte-gated field-effect transistor (EGFET) ingress into the gate dielectric, they induce a charge in the channel. The developed method works by replacing the gate dielectric with a layer under test (LUT), measuring the induced charge, and relating it to ion transport parameters. Scalability is achieved with a silicon-based sensor die on which the LUT can be deposited and an easy-to-use experimental setup. Four different EGFET devices and an integrated biasing technique are incorporated on the die to ensure functionality across a wide range of LUTs, ion species, and experimental conditions. Based on a drift–diffusion transport model, a novel working model was developed, which enables extraction of ion diffusion coefficients independently of experimental conditions. Together, the sensor, setup and model form a versatile and scalable platform for studying various combinations of LUTs and ion species.