Thermoreflectance Microscopy Measurements Of The Joule Heating Characteristics Of High-TC Superconducting Terahertz Emitters

Abstract

Joule heating is the central issue in order to develop high-power and high-performance terahertz (THz) emission from mesa devices employing the intrinsic Josephson junctions in a layered high transition-temperature Tc superconductor. Here, we describe a convenient local thermal measurement technique using charge-coupled-device-based thermoreflectance microscopy, with the highest spatial resolution to date. This technique clearly proves that the relative temperature changes of the mesa devices between different bias points on the current-voltage characteristics can be measured very sensitively. In addition, the heating characteristics on the surface of the mesa devices can be detected more directly without any special treatment of the mesa surface such as previous coatings with SiC micro-powders. The results shown here clearly indicate that the contact resistance strongly affects the formation of an inhomogeneous temperature distribution on the mesa structures. Since the temperature and sample dependencies of the Joule heating characteristics can be measured quickly, this simple thermal evaluation technique is a useful tool to check the quality of the electrical contacts, electrical wiring, and sample defects. Thus, this technique could help to reduce the heating problems and to improve the performance of superconducting THz emitter devices.

Publication Date

12-21-2017

Publication Title

Journal of Applied Physics

Volume

122

Issue

23

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1063/1.5002743

Socpus ID

85040109048 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85040109048

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