Probing the interface of Fe3O4/GaAs thin films by hard x-ray photoelectron spectroscopy

TL;DR

This study uses hard X-ray photoelectron spectroscopy to analyze the chemical interface of Fe3O4 thin films on GaAs, revealing how growth conditions affect oxidation and intermixing, which are critical for spin injection efficiency.

Contribution

It demonstrates the application of HAXPES to probe the chemical states at the Fe3O4/GaAs interface, providing insights into how growth conditions influence interface composition.

Findings

Presence of metallic Fe, As2O3, and Ga2O3 at the interface.

Interface oxidation and intermixing depend on growth conditions.

Potential impact on spin injection from magnetite into GaAs.

Abstract

Magnetite (Fe3O4) thin films on GaAs have been studied with HArd X-ray PhotoElectron Spectroscopy (HAXPES) and low-energy electron diffraction. Films prepared under different growth conditions are compared with respect to stoichiometry, oxidation, and chemical nature. Employing the considerably enhanced probing depth of HAXPES as compared to conventional x-ray photoelectron spectroscopy (XPS) allows us to investigate the chemical state of the film-substrate interfaces. The degree of oxidation and intermixing at the interface are dependent on the applied growth conditions; in particular, we found that metallic Fe, As2O3, and Ga2O3 exist at the interface. These interface phases might be detrimental for spin injection from magnetite into GaAs.