Atomically flat interface between a single-terminated LaAlO3 substrate and SrTiO3 thin film is insulating

TL;DR

This study demonstrates the creation of an atomically flat, insulating interface between a single-terminated LaAlO3 substrate and SrTiO3 thin film, providing insights into 2DEG formation and a method for high-quality film growth.

Contribution

It introduces a method to produce atomically flat, insulating interfaces on LaAlO3 substrates and explores their potential for studying 2DEG phenomena.

Findings

Achieved atomically flat, single-terminated LaAlO3 surface.

Grew SrTiO3 films on LaAlO3 with insulating interfaces.

Provided a new platform for 2DEG research.

Abstract

The surface termination of (100)-oriented LaAlO3 (LAO) single crystals was examined by atomic force microscopy and optimized to produce a single-terminated atomically flat surface by annealing. Then the atomically flat STO film was achieved on a single-terminated LAO substrate, which is expected to be similar to the n-type interface of two-dimensional electron gas (2DEG), i.e., (LaO)-(TiO2). Particularly, that can serve as a mirror structure for the typical 2DEG heterostructure to further clarify the origin of 2DEG. This newly developed interface was determined to be highly insulating. Additionally, this study demonstrates an approach to achieve atomically flat film growth based on LAO substrates.