Chaos at Interface Brings Order into Oxide/Silicon Structure

• Published in: Advanced functional materials Vol. 31; no. 36
• Main Authors: Averyanov, Dmitry V., Sokolov, Ivan S., Karateev, Igor A., Taldenkov, Alexander N., Kondratev, Oleg A., Parfenov, Oleg E., Tokmachev, Andrey M., Storchak, Vyacheslav G.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01-09-2021
• Subjects: Crystal structure; EuO; functional oxides; interface; Materials science; molecular beam epitaxy; Silicon; Spintronics; Substrates; Superstructures
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202104925

Integration of oxides with silicon fuses advanced functional properties with a mature technological platform. In particular, direct EuO/Si contact holds high promise for spintronics but requires single‐crystalline epitaxial films with atomically sharp interfaces. The standard approach employing regular 2D superstructures of metal atoms on the Si surface fails to meet the challenge. Here, an alternative route is designed and shown to solve the problem. This route avoids regular templates; the chaotic 2D distribution of metal atoms on the Si surface prevents stabilization of unwanted crystal orientations. Thus, the disordered submonolayer phase at the interface promotes order in oxide/Si coupling, as witnessed by a combination of diffraction techniques and high‐resolution electron microscopy. The results not only mark tangible progress in manufacturing EuO/Si contacts but also provide a general framework for monolithic integration of functional oxides with semiconductor substrates.
A low‐temperature route to synthesize functional oxides directly on silicon is proposed. It avoids the formation of regular 2D phases on the Si surface to prevent the stabilization of side products. As an illustration, the long‐standing problem of making a direct EuO/Si contact is solved—single‐crystalline EuO is epitaxially coupled to Si via an atomically sharp but disordered interface.