Study and characterization of SrTiO3 surface

TL;DR

This study investigates the electronic properties of SrTiO3 thin films fabricated by magnetron sputtering, demonstrating the formation of a 2DEG and Ti3+ states, with potential for scalable nanoelectronic applications.

Contribution

It introduces a mass-producible sputtering method for SrTiO3 films and characterizes their structural and electronic properties, including 2DEG formation, compared to single crystals.

Findings

2DEG observed at Fermi level in films and crystals

Ti3+ states formed after heating at 900°C

Films change from amorphous to polycrystalline upon heating

Abstract

The two-dimensional electron gas (2DEG) at oxides interfaces and surfaces has attracted large attention in physics and research due to its unique electronic properties and possible application in optoelectronics and nanoelectronics. The origin of 2DEGes at oxide interfaces has been attributed to the well known "polar catastrophe" mechanism. On the other hand, recently a 2DEG was also found on a clean SrTiO3(001) surface where it is formed due to oxygen vacancies. However, these 2DEG systems have been until now found mostly on atomically perfect crystalline samples usually grown by pulsed laser deposition or molecular beam epitaxy i.e. samples which are difficult to be prepared and require specific experimental conditions. Here, we report on the fabrication of SrTiO3 thin films deposited by magnetron sputtering which is suitable for mass-production of samples adapted for nanoelectronic applications. The characterization of their structural and electronic properties was done and compared to those of SrTiO3 single crystals. XRD patterns and SEM micrography show that the deposited films are amorphous and their structure changes to polycrystalline by heating them at 900 {\deg}C. Photoemission spectroscopy (XPS and UPS) was used to study the electronic properties of the films and the crystal. In both, we observe the 2DEG system at Fermi level and the formation of Ti3+ states after heating the surface at 900 {\deg}C.