Sub-unit cell layer-by-layer growth of Fe3O4, MgO, and Sr2RuO4 thin films

TL;DR

This paper demonstrates sub-unit cell layer-by-layer growth of Fe3O4, MgO, and Sr2RuO4 thin films using Pulsed Laser Deposition, monitored by RHEED, revealing multiple oscillations per unit cell for complex oxides.

Contribution

It introduces a method to observe sub-unit cell growth in complex oxides via RHEED oscillations during PLD, advancing epitaxial control.

Findings

Multiple RHEED oscillations per unit cell for complex oxides.

Sub-unit cell growth can be monitored in real-time.

Layer-by-layer growth of complex oxides achieved.

Abstract

The use of oxide materials in oxide electronics requires their controlled epitaxial growth. Recently, it was shown that Reflection High Energy Electron Diffraction (RHEED) allows to monitor the growth of oxide thin films even at high oxygen pressure. Here, we report the sub-unit cell molecular or block layer growth of the oxide materials Sr2RuO4, MgO, and magnetite using Pulsed Laser Deposition (PLD) from stoichiometric targets. Whereas for perovskites such as SrTiO3 or doped LaMnO3 a single RHEED intensity oscillation is found to correspond to the growth of a single unit cell, in materials where the unit cell is composed of several molecular layers or blocks with identical stoichiometry, a sub-unit cell molecular or block layer growth is established resulting in several RHEED intensity oscillations during the growth of a single unit-cell.