[Paper Review] Band Structure of EuO/Si Spin Contact: Justification for Silicon Spintronics

L. L. Lev, Dmitry V. Averyanov+5 more|arXiv (Cornell University)|Mar 15, 2016

Rare-earth and actinide compounds3 citations

TL;DR

This study investigates the electronic band structure of the EuO/Si heterojunction using soft-X-ray angle-resolved photoemission spectroscopy (ARPES) to assess its suitability for silicon spintronics. The key finding is a conduction band offset of 1.0 eV at the interface, confirming the system's technological potential for efficient spin-polarized carrier injection into silicon.

ABSTRACT

Silicon spintronics requires injection of spin-polarized carriers into Si. An emerging approach is direct electrical injection from a ferromagnetic semiconductor - EuO being the prime choice. Functionality of the EuO/Si spin contact is determined by the interface band alignment. In particular, the band offset should fall within the 0.5-2 eV range. We employ soft-X-ray ARPES to probe the electronic structure of the buried EuO/Si interface with momentum resolution and chemical specificity. The band structure reveals a conduction band offset of 1.0 eV attesting the technological potential of the EuO/Si system.

Motivation & Objective

• To evaluate the band alignment at the EuO/Si heterointerface for application in silicon spintronics.
• To determine whether the band offset at the EuO/Si interface falls within the optimal 0.5–2 eV range for spin-polarized carrier injection.
• To provide direct experimental evidence of the electronic structure of the buried EuO/Si interface with momentum resolution and chemical specificity.
• To justify the use of EuO as a ferromagnetic semiconductor contact for spin injection into silicon.

Proposed method

• Employed soft-X-ray angle-resolved photoemission spectroscopy (ARPES) to probe the electronic structure of the buried EuO/Si interface.
• Used momentum-resolved measurements to access the band dispersion and chemical state of the interface.
• Performed analysis with chemical specificity to distinguish contributions from EuO and Si components.
• Measured the conduction band offset directly from the band edge alignment at the interface.
• Utilized high-energy photons to penetrate the surface and access the buried heterointerface.

Experimental results

Research questions

• RQ1 What is the precise conduction band offset at the EuO/Si heterojunction?
• RQ2 Does the band alignment at the EuO/Si interface support efficient spin-polarized carrier injection into silicon?
• RQ3 Can soft-X-ray ARPES provide reliable, momentum-resolved electronic structure information for a buried semiconductor heterojunction?
• RQ4 Is the band offset within the technologically viable range of 0.5–2 eV for spintronic applications?

Key findings

• The conduction band offset at the EuO/Si interface was experimentally determined to be 1.0 eV.
• This value falls within the optimal 0.5–2 eV range required for efficient spin-polarized carrier injection into silicon.
• The band alignment was measured with momentum resolution and chemical specificity using soft-X-ray ARPES.
• The results confirm the technological feasibility of the EuO/Si system as a spin contact in silicon spintronics.
• The buried interface electronic structure was probed directly, validating the use of EuO as a ferromagnetic semiconductor for spin injection.