Baki Aykut, Abdeldayem Mohamed, Morales Carlos, Flege Jan Ingo, Klimm Detlef, Bierwagen Oliver, Schwarzkopf Jutta
Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, Germany.
Brandenburgische Technische Universität Cottbus-Senftenberg, FG Angewandte Physik und Halbleiterspektroskopie, Konrad-Zuse-Straße 1, 03046 Cottbus, Germany.
Cryst Growth Des. 2023 Mar 16;23(4):2522-2530. doi: 10.1021/acs.cgd.2c01438. eCollection 2023 Apr 5.
La-doped SrTiO thin films with high structural quality were homoepitaxially grown by the metal-organic vapor phase epitaxy (MOVPE) technique. Thermogravimetric characterization of the metal-organic precursors determines suitable flash evaporator temperatures for transferring the liquid source materials in the gas phase of the reactor chamber. An adjustment of the charge carrier concentration in the films, which is necessary for optimizing the thermoelectric power factor, was performed by introducing a defined amount of the metal-organic compound La(tmhd) and tetraglyme to the liquid precursor solution. X-ray diffraction and atomic force microscopy verified the occurrence of the pure perovskite phase exhibiting a high structural quality for all La concentrations. The electrical conductivity of the films obtained from Hall-effect measurements increases linearly with the La concentration in the gas phase, which is attributed to the incorporation of La ions on the Sr perovskite sites by substitution inferred from photoemission spectroscopy. The resulting structural defects were discussed concerning the formation of occasional Ruddlesden-Popper-like defects. The thermoelectric properties determined by Seebeck measurements demonstrate the high potential of SrTiO thin films grown by MOVPE for thermoelectric applications.
采用金属有机气相外延（MOVPE）技术同质外延生长出具有高结构质量的掺镧钛酸锶薄膜。对金属有机前驱体进行热重表征，确定了在反应室气相中转移液体源材料时合适的闪蒸器温度。通过向液体前驱体溶液中引入一定量的金属有机化合物La(tmhd)和四甘醇二甲醚，对薄膜中的载流子浓度进行了调整，这对于优化热电功率因数是必要的。X射线衍射和原子力显微镜证实，对于所有La浓度，均出现了具有高结构质量的纯钙钛矿相。通过霍尔效应测量得到的薄膜电导率随气相中La浓度呈线性增加，这归因于从光电子能谱推断出的La离子通过取代作用掺入到Sr钙钛矿位点上。针对偶尔形成的类Ruddlesden-Popper缺陷的形成，对产生的结构缺陷进行了讨论。通过塞贝克测量确定的热电性能表明，通过MOVPE生长的钛酸锶薄膜在热电应用方面具有很高的潜力。
