title: Generalized four-point characterization method using capacitive and ohmic contacts.
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.
authors.affiliation: Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Kim
authors.forename: Wang
authors.initials: W
authors.lastname: Zhou
authors.forename: Yash D
authors.initials: YD
authors.lastname: Shah
authors.forename: Chuanle
authors.initials: C
authors.lastname: Zhou
authors.forename: N
authors.initials: N
authors.lastname: Işık
authors.forename: M
authors.initials: M
authors.lastname: Grayson