Interface Engineering to Create a Strong Spin Filter Contact to Silicon.

C Caspers,C Besson,K Z Rushchanskii,M Müller,M Ležaić,M Gorgoi,W Drube,C S Fadley,A Gloskovskii,M Luysberg

doi:10.1038/srep22912

Abstract

Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on silicon is a perfect route to enrich silicon nanotechnology with spin filter functionality. To date, the inherent chemical reactivity between EuO and Si has prevented a heteroepitaxial integration without significant contaminations of the interface with Eu silicides and Si oxides. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive EuO/Si interface: (i) an in situ hydrogen-Si (001) passivation and (ii) the application of oxygen-protective Eu monolayers–without using any additional buffer layers. By careful chemical depth profiling of the oxide-semiconductor interface via hard x-ray photoemission spectroscopy, we show how to systematically minimize both Eu silicide and Si oxide formation to the sub-monolayer regime–and how to ultimately interface-engineer chemically clean, heteroepitaxial and ferromagnetic EuO/Si (001) in order to create a strong spin filter contact to silicon.

Highlights

O directly with Silicon wafers– paving the way for a seamless integration of spin-functional magnetic oxides with Silicon nanotechnology
Three complementary optimization studies of the EuO/Si (001) interface correlating chemical (HAXPES), structural (LEED, reflection high-energy electron diffraction (RHEED)) and magnetic (SQUID) characteristics were conducted based on atomic Eu- and H-Si (001) passivations, respectively
As a function of these interface passivations, we evaluated the Si 1s, 2p and Eu 3d core level spectra for quantification of the Si oxides SiO2−δ and Eu silicides EuSi2 at the buried EuO/Si interfaces

Summary

Introduction

O directly with Silicon wafers– paving the way for a seamless integration of spin-functional magnetic oxides with Silicon nanotechnology. Three complementary optimization studies of the EuO/Si (001) interface correlating chemical (HAXPES), structural (LEED, RHEED) and magnetic (SQUID) characteristics were conducted based on atomic Eu- and H-Si (001) passivations, respectively.

Results

Conclusion