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Magnetic Oxide Heterostructures: EuO on Cubic Oxides ... - JuSER
Magnetic Oxide Heterostructures: EuO on Cubic Oxides ... - JuSER
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5.5. Interface engineering III: SiO x passivation of the EuO/Si interface 117<br />
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I. minimize silicides<br />
EuO / pure Si<br />
EuO / H-Si<br />
II. minimize Si oxide<br />
EuO / Eu Si<br />
III. combined<br />
optimization<br />
EuO / Eu H-Si<br />
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Figure 5.26.: Summary of EuO/Si interface optimization including silicides, SiO x , and the combination<br />
of them. The aim of the optimization is to reduce interface contaminants into the greenshaded<br />
slot of silicide and SiO x thicknesses.<br />
(I) Silicide minimization is accomplished by the tuning of the synthesis temperature and the surface<br />
hydrogen termination of Si (001). (II) Silicon oxides are diminished by protective monolayers<br />
of Eu on Si (001). (III) Finally, optimum parameters including H-Si and a protective Eu<br />
monolayer are checked against synthesis temperature to yield a combined optimization accounting<br />
for both the silicides and SiO x .<br />
for the synthesis of EuO on passivated Si (001) heterostructures:<br />
H-passivated Si (001), 2 ML protective Eu, a medium T S = 450 ◦ C.<br />
During all three studies, EuO on Si (001) could be observed to grow heteroepitaxially on Si<br />
(001) by RHEED. The sharpest EuO diffraction pattern are observed in the combined passivation<br />
series – this is due to the net contamination (EuSi 2 + SiO x ) being smallest only in this<br />
combined interface optimization series.<br />
5.5. Interface engineering III: SiO x passivation of the EuO/Si interface<br />
The challenge to prevent metallic contaminations at the EuO/Si interface involves two major<br />
aspects: the avoidance of (i) silicides due to Eu–Si reactions, and (ii) excess Eu from a<br />
seed layer for EuO synthesis in order to initialize the Eu distillation growth. We address<br />
these issues by an alternative passivation method, the in situ application of ultrathin SiO x in