Thermoreflectance imaging of sub 100 ns pulsed cooling in high-speed thermoelectric microcoolers
Date of this Version
3-14-2013Citation
J. Appl. Phys. 113, 104502 (2013)
Abstract
Miniaturized thin film thermoelectric coolers have received considerable attention as potential means to locally address hot spots in microprocessors. Given the highly dynamic workload in complex integrated circuits, the need arises for a thorough understanding of the high-speed thermal behavior of microcoolers. Although some prior work on transient Peltier cooling in pulsed operation is available, these studies mostly focus on theoretical modeling and typically deal with relatively large modules with time constants well into the millisecond range. In this paper, we present an extensive experimental characterization of 30 x 30 mu m(2) high-speed coplanar SiGe superlattice microcoolers subjected to 300 ns wide current pulses at approximate to 300 kHz repetition rate. Using thermoreflectance imaging microscopy, we obtain 2D maps of the transient surface temperature and constituent Peltier and Joule components over the 50-750 ns time range with submicron spatial and 50 ns temporal resolutions. Net cooling of 1 K-1.5K is achieved within 100-300 ns, well over an order of magnitude faster compared to previous reports on microcoolers in high-speed operation. We also point out ambiguities in separating Peltier and Joule signals during the device turn-off. Overall, our measurements provide substantial insight into ultrafast turn-on and turn-off dynamics in thin film thermoelectrics. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794166]
Discipline(s)
Nanoscience and Nanotechnology
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Copyright (year) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 113, 104502 (2013) and may be found at http://dx.doi.org/10.1063/1.4794166. The following article has been submitted to/accepted by Journal of Applied Physics. Copyright (2013) Bjorn Vermeersch, Je-Hyeong Bahk, James Christofferson and Ali Shakouri. This article is distributed under a Creative Commons Attribution 3.0 Unported License.