Surface state at $BaSnO_3$ evidenced by angle-resolved photoemission spectroscopy and ab initio calculations

TL;DR

This study uncovers a 2D metallic surface state in La-doped BaSnO3 using photoemission spectroscopy and calculations, revealing potential for enhanced conductivity in optoelectronic devices.

Contribution

It provides the first direct evidence of a surface state in BaSnO3, characterized by distinct electronic properties, advancing understanding of its surface physics for device applications.

Findings

Existence of a 2D metallic surface state at BaSnO3 surface.

Surface state has a smaller effective mass (~0.12m_e) than bulk.

Surface state could improve heterostructure conductivity.

Abstract

Perovskite alkaline earth stannates, such as $BaSnO_3$ and $SrSnO_3$, showing light transparency and high electrical conductivity (when doped), have become promising candidates for novel optoelectrical devices. Such devices are mostly based on hetero-structures and understanding of their electronic structure, which usually deviates from the bulk, is mandatory for exploring a full application potential. Employing angle-resolved photoemission spectroscopy and ab initio calculations we reveal the existence of a 2-dimensional metallic state at the $SnO_2$-terminated surface of a 1\% La-doped $BaSnO_3$ thin film. The observed surface state is characterized by distinct carrier density and a smaller effective mass in comparison with the corresponding bulk values. The small surface effective mass of about $0.12m_e$ can cause an improvement of the electrical conductivity of BSO based heterostructures.