Electrical Properties of 6 nm to 19 nm Thick Polyethylene Oxide Capacitors for Ion/Electron Functional Devices

The impedance–frequency and capacitance–voltage characteristics of metal/polyethylene oxide (PEO)/Si (MOS) capacitors at thicknesses relevant to transistor technology are measured with and without CsClO4. Basic understanding of the impedance frequency and voltage characteristics of this MOS system is established in spin-coated films in the thickness range from 6 nm to 19 nm, as determined from capacitance measurements and transmission electron microscopy. Estimates of the dielectric constant, energy band diagram, charge trap density, and conductivity in ultrathin PEO are obtained. Simple equivalent circuits based on resistive and capacitive elements that reflect the physical system are used to model the measured impedance frequency trends and compare films with and without CsClO4 in the polymer matrix. This study reveals the electrical properties of PEO near the limits of thickness scaling, toward memory and neuromorphic device applications.