δ‐Doping Effects on Electronic and Energetic Properties of LaAlO₃/SrTiO₃ Heterostructure: First‐Principles Analysis of 23 Transition‐Metal Dopants

Abstract

of efforts have been invested to develop the LaAlO 3 /SrTiO 3 -based devices such as rectifying junctions, [9] photodetector, [10] single-electron transistor, [11] and fieldeffect transistors. [12,13] Despite the versatile functionality of the LaAlO 3 /SrTiO 3 HS, its practical application is still largely impeded because of its low room-temperature electron mobility (6-10 cm 2 V −1 s −1 ). [14,15] Hence, it is essential to improve the room-temperature 2DEG mobility of the LaAlO 3 /SrTiO 3 HS for further practical applications. Meanwhile, other SrTiO 3based HS have also been explored to find high electron mobility oxide materials. Notable systems are γ-Al 2 O 3 /SrTiO 3 and CaZrO 3 /SrTiO 3 , [16,17] the electron mobilities of which are much higher than that in the LaAlO 3 /SrTiO 3 HS.In principle, the electron mobility can be improved either by increasing scattering time (also called relaxation time) or by reducing electron effective mass. Accordingly, there are several mainstream approaches proposed to improve the electron mobility in the LaAlO 3 /SrTiO 3 HS system. One strategy is to tune the epitaxial strain at the interface including several top layers in the substrate or in the films, which can affect the structural distortion and strain at the interfacial region and thus manipulate electronic properties. It has been experimentally and theoretically proven that controlling the epitaxial strain is one effective way to tune the interfacial charge carrier density. [18][19][20][21][22][23] Actually, a small lattice mismatch between the film and the substrate is expected to improve the crystalline quality of the heterointerface, thus increases the scattering time and accordingly electron mobility, which is extremely difficult to accurately quantify from first-principles calculations, though. For example, very recently, Ariando and co-workers have reported that by replacing LaAlO 3 with cubic (La 0.3 Sr 0.7 ) (Al 0.65 Ta 0.35 )O 3 (LSAT), the lattice mismatch between the film and the SrTiO 3 substrate is reduced from 3.0% to 1.0%, and interfacial electron mobility can be significantly improved (about 35 000 cm 2 V −1 s −1 at 2 K), which is almost 30 times larger than that in the conventional LaAlO 3 /SrTiO 3 . [24] One the other hand, Gunkel et al. [25] proposed that the reduced epitaxial strain in LSAT/SrTiO 3 has only minor effects on the improved mobility. They attributed the increased electron mobility to the suppression of the defects at the interface, which corresponds The 2D electron gas (2DEG) formed at the interface between two insulating perovskite oxides such as LaAlO 3 and SrTiO 3 provides a playground for developing all-oxide electronic devices, though improving the 2DEG mobility is still a great challenge. One possible way of improving the 2DEG mobility is via δ-doping at the heterointerface. As a proof of concept, one recent experiment achieves an ultra-high 2DEG mobility of 73 000 cm 2 V −1 s −1 at the LaAlO 3 / SrTiO 3 heterointerface via Mn δ-doping. Here the electronic and energetic properties ...

High-throughput prediction of oxygen vacancy defect migration near misfit dislocations in SrTiO3/BaZrO3 heterostructures

“…Perovskite oxide heterostructures have gained popularity due to their versatility in diverse technologies, including SOFCs. Depending on the desired application, perovskites are often doped to enhance magnetic, 21 ionic, 22 electronic, 23 optical, and catalytic 24 properties. Among various perovskite oxides, SrTiO 3 (STO) 25 and BaZrO 3 (BZO) have been frequently studied, wherein doping is used to tune their functionality.…”

Atomically Thin 2D Transition Metal Oxides: Structural Reconstruction, Interaction with Substrates, and Potential Applications

“…In contrast, the weak magnetism found in more conductive LaAlO 3 /SrTiO 3 heterostructures prepared at low oxygen partial pressure is due to the formation of surface oxygen vacancies alone. Apart from the above efforts made to understand the electronic and magnetic reconstruction in the LaAlO 3 /SrTiO 3 heterostructures, an extensive number of attempts have been made to tune the multidegree coupling at the interface, which includes interfacial strain, doping, ferroelectric substrates, or gate voltage . All these not only enrich the understanding of the complex oxide interfaces, but also shed light on further functionalization and potential applications of these strategic oxide heterostructures …”

Influence of Chemistry and Misfit Dislocation Structure on Dopant Segregation at Complex Oxide Heterointerfaces

“…Doping is characteristically used as an effective route to alter, and in some cases control, the properties of oxides. Contingent on the specific demands of a given application, addition of various types of dopants leads to enhancement in magnetic, ionic, electronic, and catalytic properties of oxides. For instance, Suyolcu et al .…”