Oxide two-dimensional electron gas with high mobility at room-temperature

TL;DR

This paper demonstrates the formation of a high-mobility two-dimensional electron gas at the LaScO3/BaSnO3 interface with room-temperature mobility significantly higher than previous oxide 2DEGs, using advanced growth and imaging techniques.

Contribution

It reports the first high-mobility 2DEG in BaSnO3-based heterostructures at room temperature, achieved through optimized growth and surface treatment methods.

Findings

Room-temperature mobility of 60 cm2/V s at the BSO/LSO interface.

Order of magnitude higher mobility than SrTiO3-based 2DEGs.

Reduction of threading dislocation density confirmed by imaging techniques.

Abstract

The prospect of 2-dimensional electron gases (2DEGs) possessing high mobility at room temperature in wide-bandgap perovskite stannates is enticing for oxide electronics, particularly to realize transparent and high-electron mobility transistors. Nonetheless only a small number of studies to date report 2DEGs in BaSnO3-based heterostructures. Here, we report 2DEG formation at the LaScO3/BaSnO3 (LSO/BSO) interface with a room-temperature mobility of 60 cm2/V s at a carrier concentration of 1.7x1013 cm-2. This is an order of magnitude higher mobility at room temperature than achieved in SrTiO3-based 2DEGs. We achieved this by combining a thick BSO buffer layer with an ex-situ high-temperature treatment, which not only reduces the dislocation density but also produces a SnO2-terminated atomically flat surface, followed by the growth of an overlying BSO/LSO interface. Using weak-beam dark field imaging and in-line electron holography technique, we reveal a reduction of the threading dislocation density, and provide direct evidence for the spatial confinement of a 2DEG at the BSO/LSO interface. Our work opens a new pathway to explore the exciting physics of stannate-based 2DEGs at application-relevant temperatures for oxide nanoelectronics.