Growth of α-Sn on silicon by a reversed β-Sn to α-Sn phase transformation for quantum material integration

• Main Authors: Akey, A. (Author), Covian, A.C (Author), Gardener, J.A (Author), Levin, B.D.A (Author), Liu, J. (Author), Liu, S. (Author), Wang, X. (Author)
• Format: Article
• Language: English
• Published: Springer Nature 2022
• Subjects: Deposited materials; Germanium; Germaniums (Ge); Integration; Large lattice mismatch; Lattice mismatch; Native oxides; Oxide layer; Phase transitions; Phases transformation; Semiconductor alloys; Si-Ge alloys; Silicon; Silicon substrates; Sn-doped; Thermodynamically stable; Tin alloys; Topology; β-Sn
• Online Access: View Fulltext in Publisher

 α-Sn and SnGe alloys are attracting attention as a new family of topological quantum materials. However, bulk α-Sn is thermodynamically stable only below 13∘C. Moreover, scalable integration of α-Sn quantum materials and devices on silicon is hindered by their large lattice mismatch. Here, we grow compressively strained α-Sn doped with 2-4 at.% germanium on a native oxide layer on a silicon substrate at 300–500∘C. Growth is found to occur by a reversed β-Sn to α-Sn phase transformation without relying on epitaxy, with germanium-rich GeSn nanoclusters in the as-deposited material acting as seeds. The size of α-Sn microdots reaches up to 200 nm, which is approximately ten times larger than the upper size limit for α-Sn formation reported previously. Furthermore, the compressive strain makes it a candidate 3D topological Dirac semimetal with possible applications in spintronics. This process can be further optimized to achieve optically tunable SnGe quantum material and device integration on silicon. © 2022, The Author(s).