Generalized four-point characterization method using capacitive and ohmic contacts

Brian S. Kim, Wang Zhou, Yash D. Shah, Chuanle Zhou, N. Işik, M. Grayson*

*Corresponding author for this work

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

In this paper, a four-point characterization method is developed for samples that have either capacitive or ohmic contacts. When capacitive contacts are used, capacitive current- and voltage-dividers result in a capacitive scaling factor not present in four-point measurements with only ohmic contacts. From a circuit equivalent of the complete measurement system, one can determine both the measurement frequency band and capacitive scaling factor for various four-point characterization configurations. This technique is first demonstrated with a discrete element four-point test device and then with a capacitively and ohmically contacted Hall bar sample over a wide frequency range (1 Hz-100 kHz) using lock-in measurement techniques. In all the cases, data fit well to a circuit simulation of the entire measurement system, and best results are achieved with large area capacitive contacts and a high input-impedance preamplifier stage. An undesirable asymmetry offset in the measurement signal is described which can arise due to asymmetric voltage contacts.

Original languageEnglish (US)
Article number024703
JournalReview of Scientific Instruments
Volume83
Issue number2
DOIs
StatePublished - Feb 2012

ASJC Scopus subject areas

  • Instrumentation

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