Mott-Schottky Analysis of Passive Films on Zinc by Electrochemical Impedance Spectroscopy under Potential Control

摘要

Generally, Mott-Schottky analysis on semiconducting materials is carried out by measurement of the impedance at different applied potentials using a single frequency. Thus, a simple capacity model is underlying the data evaluation and only one physical process for the sample is assumed to determine the measured impedance, e.g. variation of space charge layer thickness with potential. Electrochemically active materials exhibit a more complicated behaviour and other processes might influence the impedance at the chosen frequency. Therefore, measurement of the impedance spectrum in a wide range of frequencies would be desirable. Unfortunately, impedance data might also contain errors and artifacts originating from bandwidth restrictions of the potentiostat or cross talk between electrodes in a 3-electrode configuration. In this work, we present accurate electrochemical impedance measurements on zinc oxide passive films in the frequency range from 10~(-3)Hz to 10~6Hz with simussltaneous potential control.