A consistent picture of excitations in cubic BaSnO${}_3$ revealed by combining theory and experiment

Abstract

Among the transparent conducting oxides, the perovskite barium stannate is most promising for various electronic applications due to its outstanding carrier mobility achieved at room temperature. However, most of its important characteristics, such as band gaps, effective masses, and absorption edge, remain controversial. Here, we provide a fully consistent picture by combining state-of-the-art {\it ab initio} methodology with forefront electron energy-loss spectroscopy and optical absorption measurements. Valence electron energy-loss spectra, featuring signals originating from band gap transitions, are acquired on defect-free sample regions of a BaSnO${}_3$ single crystal. These high-energy-resolution measurements are able to capture also very weak excitations below the optical gap, attributed to indirect transitions. By temperature-dependent optical absorption measurements, we assess band-gap renormalization effects induced by electron-phonon coupling. Overall, we find for the effective electronic mass, the direct and the indirect gap, the optical gap, as well as the absorption onsets and spectra, excellent agreement between both experimental techniques and the theoretical many-body results, supporting also the picture of a phonon-mediated mechanism where indirect transitions are activated by phonon-induced symmetry lowering. This work demonstrates a fruitful connection between different high-level theoretical and experimental methods for exploring the characteristics of advanced materials.

References in corpus (9)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• High Mobility in a Stable Transparent Perovskite Oxide
• Physical properties of transparent perovskite oxides (Ba,La)SnO3 with high electrical mobility at room temperature
• Transparent perovskite barium stannate with high electron mobility and thermal stability
• Vibrational Effects in X-ray Absorption Spectra of 2D Layered Materials
• Tuning two-dimensional electron (hole) gases at LaInO${}_3$/BaSnO${}_3$ interfaces: Impact of polar distortions, termination, and thickness
• Fingerprints of optical absorption in the perovskite LaInO${}_3$: Insight from many-body theory and experiment
• Electronic band structure of narrow-bandgap p-n nanojunctions in heterostructured nanowires measured by electron energy loss spectroscopy

Cited by in corpus (3)

• Optical absorption spectra of metal oxides from time-dependent density functional theory and many-body perturbation theory based on optimally-tuned hybrid functionals
• Tuning two-dimensional electron (hole) gases at LaInO${}_3$/BaSnO${}_3$ interfaces: Impact of polar distortions, termination, and thickness
• Epitaxial Films and Devices of Transparent Conducting Oxides: La:BaSnO${}_3$