New approach in the growth of thin films of Selenides (P and N Type) with high figures of merit

Abstract

It has been reported crystalline p-type Cu2Se bulk material has been synthesized with excellent thermoelectric properties with a unusual combination of properties leads to an ideal thermoelectric material within the new concept of `Phonon-liquid electron-crystal¿ [1]. We report a novel approach on the growth of highly efficient thermoelectric materials via pulse controlled reactive magnetron sputtering. This technique allows for a finer control of the stoichiometry, crystallographic orientation, etc. and it is a very fast production technique. It is shown to be fully reproducible and scalable to industry. The fabrication method is a low temperature process, and thus allows the use of organic and/or flexible substrates to deposit the films on them, which opens a whole new field of applications that are not possible with other fabrication techniques. We have focused in the deposit of Cu2-xSe and Ag2-xSe films, obtaining high values in the power factor (1.1 mW¿m-1¿ K-2) for the cubic ß-Cu2Se phase and (2.5 mW¿m-1¿ K-2) for the cubic ß-Ag2Se phase compared with the highest reported in the literature for both bulk and higher than films. [1] H. Liu et al., Nature Materials 11, 422 (2012).