Thermoelectric La-doped SrTiO 3 epitaxial layers with single-crystal quality: from nano to micrometers

Sci Technol Adv Mater. 2017 Jun 20;18(1):430-435. doi: 10.1080/14686996.2017.1336055. eCollection 2017.

Abstract

High-quality thermoelectric La0.2Sr0.8TiO3 (LSTO) films, with thicknesses ranging from 20 nm to 0.7 μm, have been epitaxially grown on SrTiO3(001) substrates by enhanced solid-source oxide molecular-beam epitaxy. All films are atomically flat (with rms roughness < 0.2 nm), with low mosaicity (<0.1°), and present very low electrical resistivity (<5 × 10-4 Ω cm at room temperature), one order of magnitude lower than standard commercial Nb-doped SrTiO3 single-crystalline substrate. The conservation of transport properties within this thickness range has been confirmed by thermoelectric measurements where Seebeck coefficients of approximately -60 μV/K have been recorded for all films. These LSTO films can be integrated on Si for non-volatile memory structures or opto-microelectronic devices, functioning as transparent conductors or thermoelectric elements.

Keywords: 201 Electronics / Semiconductor / TCOs; 210 Thermoelectronics / Thermal transport / insulators; 302 Crystallization / Heat treatment / Crystal growth; 306 Thin film / Coatings; 50 Energy materials; Functional oxides; Integrated films; La-doped SrTiO3; Molecular beam epitaxy; Thermoelectricity.