AVS 57th International Symposium & Exhibition
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuA

Paper SE-TuA9
Thermal Conductance of Pt/VO2/Pt Heterointerfaces

Tuesday, October 19, 2010, 4:40 pm, Room Cimmaron

Session: Surface Engineering for Thermal Management
Presenter: D.-W. Oh, University of Illinois at Urbana-Champaign
Authors: D.-W. Oh, University of Illinois at Urbana-Champaign
D.G. Cahill, University of Illinois at Urbana-Champaign
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The metal-insulator-transition (MIT) of VO2 at ≈68°C allows us to systematically explore heat transport at interfaces between metals and correlated-electron systems. We use time domain thermoreflectance (TDTR) to measure interfacial thermal conductance of Pt/VO2/Pt structures. Pt/VO2/Pt layers are deposited by reactive dc sputtering on sapphire substrates. High throughput measurements of dependence of the conductance on the VO2 thickness h are enabled by creating a lateral thickness gradient, 0<h<30 nm, across the width of the sample. The thermal conductance of Pt/VO2/Pt structures with h<10 nm was found to be large (~800 MW m-2 K-1), implying that the VO2 layer is not planar. The thermal conductance of thicker VO2, h>10 nm, was ~200 MW m-2 K-1. We have not yet been able to resolve a difference in the thermal conductance between the metal and insulator phases of VO2; the upper limit on the change in conductance at the metal-to-insulator transition is ~40 MW m-2 K-1. This conductance implies that the specific electrical resistance of an interface between metallic VO2 and Pt is >2´10-8 W cm2.