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

Abstract The 2D electron gas (2DEG) formed at the interface between two insulating perovskite oxides such as LaAlO₃ and SrTiO₃ 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 cm² V⁻¹ s⁻¹ at the LaAlO₃/SrTiO₃ heterointerface via Mn δ‐doping. Here the electronic and energetic properties of δ‐doped LaAlO₃/SrTiO₃ are studied with 23 transition‐metal dopants from group 3 to group 10 using first‐principles calculations. A clear trend is found for the electron effective mass and interfacial energy change in the δ‐doped LaAlO₃/SrTiO₃ with various dopants, and there exists a trade‐off between achieving light effective mass bands and forming energetically favorable structures. It is found that the Fe, Co, Ni, Ru, Rh, Pd, Os, and Ir could also serve as promising candidate dopants to produce light effective mass bands and relatively high energetic stability, in addition to the experimentally confirmed Mn dopant. The findings of this study provide a wide avenue to increase the 2DEG mobility in the LaAlO₃/SrTiO₃ heterostructure via δ‐doping with transition metals.