Bastet

We are a partner in the Leibniz Association and the Leibniz ScienceCampus Growth and fundamentals of oxides (GraFOx) for electronic applications. Our project is focused on the ab-initio description of physical properties of BaSnO3 based heterostructures using density-functional theory (DFT) and many-body perturbation theory.

Current Projects

Structural and electronic properties of BaSnO₃/LaInO₃ interfaces

Transparent oxide semiconductors are a key material for a wide variety of electronic applications due to their rich and tunable properties. The perovskite barium stannate (BaSnO₃) has appeared in the last years as the most promising candidate due to its high electron mobility at room temperature, excellent thermal stability, and high transparency [1]. The combination of BaSnO₃ (non-polar) with structurally similar polar-oxide such as LaInO₃, is expected to generate a two-dimensional electron gas (2DEG) confined in a potential well at the interface.
Ab-initio approaches are being applied towards theoretical characterization of these interfaces. The project implies an in-depth understanding of the interface orientation, level alignment, strain effects, and surface terminations. This research is performed hand in hand with our experimental partners at the Leibniz Institute for Crystal Growth (IKZ), the Paul-Drude-Institut fur Festkörperelektronik (PDI), and the Technische Universität Berlin (TU).

Ferroelectric perovskites to tune interfacial two-dimensional electron gas (2DEG)

The two-dimensional electron gas (2DEG) formed at the interface between two insulating oxide perovskites has attracted great attention in recent years as it is promising for the next-generation of nanoelectronic devices. As such, it is desirable to have the ability to modulate the 2DEG properties by an external stimulus.
It has been found that layers of a ferroelectric material can be very efficient to control the interfacial 2DEG. Here, we consider a heterostructure formed by combining the polar perovskite LaInO₃ (LIO) with the nonpolar perovskite BaSnO₃ (BSO). In this case, the polar discontinuity leads to the formation of 2DEG at the interface within the BSO side. We investigate the impact of the inclusion of the common ferroelectric perovskite BaTiO₃ (BTO) on the density and distribution of the 2DEG. The role of the thickness of the ferroelectric material as well as the amount and direction of its polarization will be investigated.

Currently involved people

• Claudia Draxl (PI)
• Wahib Aggoune (postdoc)
• Le Fang (PhD student)

Publications

M. Zupancic, et al. Role of the interface in controlling the epitaxial relationship between orthorhombic LaInO3 and cubic BaSnO3 arXiv (preprint 2020). Epitaxial perovskite oxide interfaces with different symmetry of the epitaxial layers have attracted considerable attention due to the emergence of novel behaviors and phenomena. In this paper, we show by aberration corrected transmission electron microscopy that orthorhombic LaInO3 films grow in form of three different types of domains on the cubic BaSnO3 pseudosubstrate. Quantitative evaluation of our TEM data shows that cpc-oriented and apc/bpc-oriented domains are present with similar probability. While continuum elasticity theory suggests that cpc-oriented domains should exhibit a significantly higher strain energy density than apc/bpc-oriented domains, density functional calculations confirm that cpc- and apc-oriented domains on BaSnO3 have similar energies.