Journal Article

Oxide Two‐Dimensional Electron Gas with High Mobility at Room‐Temperature

Eom, Chang‐Beom, Eom, Kitae, Rzchowski, Mark S., Oh, Sang Ho, Schlom, Darrell G., Seo, Jinsol, Paik, Hanjong, Tsymbal, Evgeny Y., Campbell, Neil

2022

Overview

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, 2DEG formation at the LaScO3/BaSnO3 (LSO/BSO) interface with a room‐temperature mobility of 60 cm2 V−1 s−1 at a carrier concentration of 1.7 × 1013 cm–2 is reported. This is an order of magnitude higher mobility at room temperature than achieved in SrTiO3‐based 2DEGs. This is achieved 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 transmission electron microscopy imaging and in‐line electron holography technique, a reduction of the threading dislocation density is revealed, and direct evidence for the spatial confinement of a 2DEG at the BSO/LSO interface is provided. This work opens a new pathway to explore the exciting physics of stannate‐based 2DEGs at application‐relevant temperatures for oxide nanoelectronics. The promise of BaSnO3 (BSO) band structure and scattering channels to relieve low room temperature mobility challenges of interfacial oxide two‐dimensional electron gases has been blocked by structural and point defects. The authors overcome this with a new synthesis approach combining a BSO atomically flat pseudo‐substrate layer with a band‐aligned BSO/LaScO3 oxide interface.

• Publisher: John Wiley & Sons, Inc,Wiley Blackwell (John Wiley & Sons),John Wiley and Sons Inc,Wiley
• Subject: 2-dimensional electron gas / alkaline-earth stannate / INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY / Interfaces / MATERIALS SCIENCE / Point defects / room temperature high mobility / Thin films / transparent conducting oxide