Electrical Property Enhancement in Orientation‐Modulated Perovskite La‐Doped SrTiO₃ Thermoelectric Thin Films

Abstract

Thermoelectric oxide thin films are promising in chip cooling. The issues on the orientation of thin films are essential as they are related to the structures, morphologies, and thermoelectric properties. In this regard, the orientation modulation is conducted on La‐doped SrTiO3 thin films on (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) single crystal substrates. Layer‐by‐layer growth mode is found in (001)‐ and (110)‐ oriented thin films, resulting in few grain boundaries (GBs). In (111)‐oriented films, island growth mode leads to columnar grain boundaries that build up potential barriers for electrons to be strongly scattered and filtered, suppressing electron mobility and increasing effective mass. In addition, the GBs serve as oxygen vacancy diffusion paths when annealing, causing increased carrier concentration and lattice contraction. The weighted mobility of 71.9 cm2 V−1 s−1 and electrical conductivity of ≈600 S cm−1 are realized in the (001)‐oriented film at room temperature. Ultimately, outstanding power factor values of ≈569 µW m−1 K−2 (room temperature) and ≈791 µW m−1 K−2 (573 K) are successfully achieved, outperforming those in polycrystalline ceramics and (111)‐oriented films. This study systematically investigates the influence of grain boundaries and orientations on SrTiO3‐based thermoelectric films, which lays a solid foundation for improving thermoelectric performance in other oxide thin films.

Competitive Adsorption Mechanism of Defect‐Induced d‐Orbital Single Electrons in SrRuO3 for Alkaline Hydrogen Evolution Reaction

“…The observed shift of XRD peaks toward higher angles for V-SRCO could be attributed to lattice contraction caused by the generation of Vo. [31] Previous studies have shown that moderate doping is more favorable for the generation of Vo. [32,33] Moderate doping of Co atoms at the B-site in SRO, followed by etching with HCl solution, can result in the formation of Vo-rich V-SRCO.…”

Large Electrical Conductivity and Thermoelectric Power Factor of Pulsed Laser-Deposited Zn1–xGaxO Thin Films

“…Thin film thermoelectrics (TFTE) has been an intriguing avenue of investigation in the recent past due to the plethora of technological applications such as self-powered wearable electronic devices, wireless sensor networks, microelectronics cooling, integrated circuits, etc. − The potentiality of the TE thin films is evaluated via the dimensionless figure of merit , where S is the Seebeck coefficient, σ is electrical conductivity, κ is total thermal conductivity, and T is absolute temperature. − Nevertheless, achieving a high figure of merit is a key challenge due to the interdependent relationship among the physical parameters S , κ, and σ. − The simultaneous increase in Seebeck coefficient and the electrical conductivity, for a favorable enhancement of power factor (PF = S 2 σ), is tricky due to the inverse correlation of S and σ with carrier density n . Degenerately doped semiconductor thin films are the ideal choice for realizing a high TE power factor. − …”