Growth and thermoelectric properties of FeSb2 films produced by pulsed laser deposition

Abstract

FeSb2, a strongly correlated semiconductor, has promising application potential for thermoelectric cooling at cryogenic temperatures [1,2]. Single crystals of FeSb2 were found to exhibit colossal thermopower (S) values up to ~ −45000 μVK-1 and record high power factors up to 2300 μWK−2 cm−1 at 12 K [2]. However, the thermoelectric performance of FeSb2 is restricted by its large lattice thermal conductivity (κL). Thin film thermoelectric materials could have a much reduced κL due to surface and grain-boundary scattering of phonons. Therefore, FeSb2 thin films are expected to have remarkably enhanced thermoelectric performance. Herein, FeSb2 films were produced on silica substrates in a low-pressure Ar environment by a pulsed Nd:YAG laser at 355 nm. The effect of growth parameters, such as substrate temperature, Ar pressure, incident fluence and growth time, on the PLD growth of FeSb2 was systematically studied. Uniform, continuous and nearly phase-pure FeSb2 films with thickness of 100-400 nm were produced. Thermal transport and Hall measurements were performed to study their thermoelectric transport properties. A maximum absolute value of S ~120 μVK-1 at 40 K was obtained. This study should serve to strengthen the interest in application of FeSb2 films in thermoelectrics. 1. P. Sun, N. Oeschler, S. Johnsen, B. B. Iversen, F. Steglich. Dalton Trans. 39 (2010) 965. 2. A. Bentien, S. Johnsen, G. K. H. Madsen, B. B. Iversen, F. Steglich, Europhys. Lett. 80 (2007) 17008