Generalized four-point characterization method for resistive and capacitive contacts

TL;DR

This paper introduces a generalized four-point measurement method for resistive samples with resistive or capacitive contacts, enabling accurate characterization across a wide frequency range by accounting for system capacitances and impedances.

Contribution

It develops a novel four-point characterization technique that incorporates system capacitances and impedances, extending low-frequency resistive contact analysis to capacitive contacts.

Findings

Method accurately characterizes resistive samples with capacitive contacts.

System capacitances and impedances can be effectively incorporated into the measurement.

High impedance preamplifiers improve measurement accuracy.

Abstract

In this paper, a four-point characterization method is developed for resistive samples connected to either resistive or capacitive contacts. Provided the circuit equivalent of the complete measurement system is known including coaxial cable and connector capacitances as well as source output and amplifier input impedances, a frequency range and capacitive scaling factor can be determined, whereby four-point characterization can be performed. The technique is demonstrated with a discrete element test sample over a wide frequency range using lock-in measurement techniques from 1 Hz - 100 kHz. The data fit well with a circuit simulation of the entire measurement system. A high impedance preamplifier input stage gives best results, since lock-in input impedances may differ from manufacturer specifications. The analysis presented here establishes the utility of capacitive contacts for four-point characterizations at low frequency.