In-plane thermal conductivity of disordered layered WSe2 and (W)x(WSe2)y superlattice films

It was recently reported that misoriented layered WSe2 and (W)x(WSe2)y films possess extremely low cross-plane thermal conductivity. Here, we report that the in-plane thermal conductivity results for WSe2 and W4(WSe2)10 films measured by using a suspended device are about 30 times higher than the cross-plane values because of the in-plane ordered and cross-plane disordered structures and about six times lower than that of compacted single-crystal WSe2 platelets. The additional W layers in the W4(WSe2)10 films were found to greatly increase the in-plane electrical conductivity relative to the WSe2 films, but reduce the in-plane lattice thermal conductivity assuming the Wiedemann-Franz law.

[1]  Mehdi Asheghi,et al.  Thermal Conductivity Measurements of Ultra-Thin Single Crystal Silicon Layers , 2006 .

[2]  M. P. Walsh,et al.  Quantum Dot Superlattice Thermoelectric Materials and Devices , 2002, Science.

[3]  Jun Li,et al.  Thermal Contact Resistance and Thermal Conductivity of a Carbon Nanofiber , 2006 .

[4]  Li Shi,et al.  Measuring Thermal and Thermoelectric Properties of One-Dimensional Nanostructures Using a Microfabricated Device , 2003 .

[5]  R. Venkatasubramanian,et al.  Thin-film thermoelectric devices with high room-temperature figures of merit , 2001, Nature.

[6]  Li Shi,et al.  Determination of transport properties in chromium disilicide nanowires via combined thermoelectric and structural characterizations. , 2007, Nano letters.

[7]  D. Cahill.  Analysis of heat flow in layered structures for time-domain thermoreflectance , 2004 .

[8]  D. Cahill.  Thermal conductivity measurement from 30 to 750 K: the 3ω method , 1990 .

[9]  Kenneth E. Goodson,et al.  Thermal characterization of anisotropic thin dielectric films using harmonic Joule heating , 1999 .

[10]  Bernard Revaz,et al.  Measurement of thermal conductivity of thin films with a Si-N membrane-based microcalorimeter , 2005 .

[11]  K. Goodson,et al.  Ordering Up the Minimum Thermal Conductivity of Solids , 2007, Science.

[12]  Paul Zschack,et al.  Ultralow Thermal Conductivity in Disordered, Layered WSe2 Crystals , 2007, Science.

[13]  Li Shi,et al.  Four-probe measurements of the in-plane thermoelectric properties of nanofilms. , 2007, The Review of scientific instruments.