Abstract
Misfit cobaltates ([Bi/Ba/Sr/Ca/CoO]nRS[CoO2]q) constitute the most promising family of thermoelectric oxides for high temperature energy harvesting. However, their complex structure and chemical composition makes extremely challenging their deposition by high-vacuum physical techniques. Therefore, many of them have not been prepared as thin films until now. Here we report the synthesis of high-quality epitaxial thin films of the most representative members of this family of compounds by a water-based chemical solution deposition method. The films show an exceptional crystalline quality, with an electrical conductivity and thermopower comparable to single crystals. These properties are linked to the epitaxial matching of the rock-salt layers of the structure to the substrate, producing clean interfaces free of amorphous phases. This is an important step forward for the integration of these materials with complementary n-type thermoelectric oxides in multilayer nanostructures.
Highlights
A single chemical method suitable for the fabrication of all the 3 and 4-layer compounds is still lacking, which limits the applicability and recognition of these techniques
We demonstrate that the quasi-equilibrium growth characteristic of this method favors the epitaxial matching between the rock salt structure (RS) lattice and the substrate, promoting a well ordered self-assembled growth along the thickness of the film, free of amorphous interfaces
The X-ray diffraction (XRD) patterns are shown in Fig. 1 for all the samples deposited in this work
Summary
A single chemical method suitable for the fabrication of all the 3 and 4-layer compounds is still lacking, which limits the applicability and recognition of these techniques. We report the chemical solution synthesis of high-quality epitaxial thin films of all the representative members of this family of compounds, including the complex 4-layer compounds.
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