Giant Tuning of Electronic and Thermoelectric Properties by Epitaxial Strain in p-Type Sr-Doped LaCrO3 Transparent Thin Films

The impact of epitaxial strain on the structural, electronic, and thermoelectric properties of p-type transparent Sr-doped LaCrO3 thin films has been investigated. For this purpose, high-quality fully strained La0.75Sr0.25CrO3 (LSCO) epitaxial thin films were grown by molecular beam epitaxy on three different (pseudo)cubic (001)-oriented perovskite oxide substrates: LaAlO3, (LaAlO3)(0.3)(Sr2AlTaO6)(0.7), and DyScO3. The lattice mismatch between the LSCO films and the substrates induces in-plane strain ranging from -2.06% (compressive) to +1.75% (tensile). The electric conductivity can be controlled over 2 orders of magnitude, with s ranging from similar to 0.5 S cm(-1) (tensile strain) to similar to 35 S cm(-1) (compressive strain). Consistently, the Seebeck coefficient S can be finely tuned by a factor of almost 2 from similar to 127 mu V K-1 (compressive strain) to 208 mu V K-1 (tensile strain). Interestingly, we show that the thermoelectric power factor (PF = S-2 sigma) can consequently be tuned by almost 2 orders of magnitude. The compressive strain yields a remarkable enhancement by a factor of 3 for 2% compressive strain with respect to almost relaxed films. These results demonstrate that epitaxial strain is a powerful lever to control the electric properties of LSCO and enhance its thermoelectric properties, which is of high interest for various devices and key applications such as thermal energy harvesters, coolers, transparent conductors, photocatalyzers, and spintronic memories.

Automated summary

The study investigates the impact of epitaxial strain on the structural, electronic, and thermoelectric properties of p-type transparent Sr-doped LaCrO3 thin films. By growing high-quality fully strained LSCO epitaxial thin films on different oxide substrates, it was found that the electric conductivity and Seebeck coefficient can be significantly influenced by strain.