Tuning thermoelectricity by epitaxial strain in (La,Sr)CrO3

The electronic and thermoelectric properties of p-type semiconducting transparent (La,Sr)CrO3 can be largely tuned by epitaxial strain.

La1-xSrxCrO3 (LSCO) solid solutions of perovskite structure are of high interest for numerous application fields because of their key original properties (p-type semiconducting, transparent, thermoelectric). In addition to their property tuning by cationic substitution x (La3+ by Sr2+), we have shown in LSCO (x = 0.25) thin films epitaxially grown by molecular beam epitaxy (MBE) that their physical properties can be also largely tuned by epitaxial strain. In the in-plane strain range of +/- 2%, the electrical conductivity can be controlled over two orders of magnitude (0.5 S/cm in tension and 35 S/cm in compression). Consistently, the Seebeck coefficient can be tuned almost within a factor two (127 microV/K in compression and 208 microV/K in tension). Consequently, the thermoelectric power factor can be tuned over two orders of magnitude, with enhancement in compression. These results are of high interest for advanced LSCO-based devices.

Contact: Romain BACHELET

References: Dong Han, Rahma Moalla, Ignasi Fina, Valentina M. Giordano, Marc d’Esperonnat, Claude Botella, Geneviève Grenet, Régis Debord, Stéphane Pailhès, Guillaume Saint-Girons, and Romain Bachelet,
“Giant Tuning of Electronic and Thermoelectric Properties by Epitaxial Strain in p-Type Sr-Doped LaCrO3 Transparent Thin Films”,
ACS Applied Electronic Materials 3, 8, 3461-3471 (2021);

Partners: – Institut de Ciencia de Materials de Barcelona (ICMAB), Barcelona, Spain
– Institut Lumière Matière (ILM), Lyon, France

Electrical conductivity and Seebeck coefficient, measured in-plane at room temperature in La0.75Sr0.25CrO3 heteroepitaxial thin films, plotted as a function of in-plane strain and associated stress.
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