On the emergence of conductivity at SrTiO3-based oxide interfaces -- an in-situ study

TL;DR

This study uses in-situ measurements to reveal that conductivity at SrTiO3-based oxide interfaces emerges earlier during growth than previously known, influenced by multiple physical processes, offering a new way to control interface properties.

Contribution

It provides the first real-time observation of interface conductivity emergence during oxide heterostructure growth, challenging prior notions of a critical thickness requirement.

Findings

Conductivity appears at the initial growth stage, earlier than ex-situ observations.

Physical processes like light, plasma bombardment, and oxygen migration influence conductivity.

Real-time control of interface properties is possible during growth.

Abstract

Heterostructures and crystal interfaces play a major role in state-of-the-art semiconductor devices and play a central role in the field of oxide electronics. In oxides the link between the microscopic properties of the interfaces and bulk properties of the resulting heterostructures challenge our fundamental understanding. Insights on the early growth stage of interfaces and its influence on resulting physical properties are scarce -- typically the information is inferred from post growth characterization. Here, we report on real time measurements of the transport properties of SrTiO3-based heterostructures while the crystal heterostructure is forming. Surprisingly, we detect a conducting interface already at the initial growth stage, much earlier than the well-established critical thickness limit for observing conductivity ex-situ after sample growth. We investigate how the conductivity depends on various physical processes occurring during pulsed laser depositions, including light illumination, particle bombardment by the plasma plume, interactions with the atmosphere and oxygen migration from SrTiO3 to the thin films of varying compositions. Using this approach, we propose a new design tool to control the electrical properties of interfaces in real time during their formation.