Semiconductor/lithium lanthanum titanate perovskite interface: a DFT study

Abstract Currently, incorporating functional materials such as Si and Ge semiconductors on perovskite-type oxide titanates is essential to exploit their electronic and magnetic properties. In this work, the electronic and magnetic properties of Si/Ge monolayer (ML) on a LaO-terminated LaTiO3 (LTO) or LiO-terminated Li0.5La0.5TiO3 (LLTO) surface, at La-, O- and Li-top sites systems were studied through the Density Functional Theory. Our results show that the system has an antiferromagnetic order when the Si-ML is on the O-top site of the LTO surface; and ferromagnetic when the Si-ML is on the O-top site of the LLTO surface. All the remaining Si adsorption cases are ferrimagnetic systems. When the Ge ML is placed at the La-top and O-top sites on the LTO surface, the resulting systems exhibit ferrimagnetism. In contrast, the Ge-ML on the LLTO surface shows ferromagnetism, regardless of the adsorption site. The adsorption energy values show that the most favorable site to place the Si/Ge ML on the LLTO perovskite surface is at the O-top site. These results display that Si/Ge semiconductor ML/oxide perovskite surface could be used as interface in electrochemical systems.