Robust topological surface states of Bi2Se3 thin films on amorphous SiO2/Si substrate and a large ambipolar gating effect

Abstract

The recent emergence of topological insulators (TI) has spurred intensive efforts to grow TI thin films on various substrates. However, little is known about how robust the topological surface states (TSS) are against disorders and other detrimental effects originating from the substrates. Here, we report observation of a well-defined TSS on Bi2Se3 films grown on amorphous SiO2 (a-SiO2) substrates and a large gating effect on these films using the underneath doped-Si substrate as the back gate. The films on a-SiO2 were composed of c-axis ordered but random in-plane domains. However, despite the in-plane randomness induced by the amorphous substrate, the transport properties of these films were superior to those of similar films grown on single-crystalline Si(111) substrates, which are structurally better matched but chemically reactive with the films. This work sheds light on the importance of chemical compatibility, compared to lattice matching, for the growth of TI thin films, and also demonstrates that the technologically-important and gatable a-SiO2/Si substrate is a promising platform for TI films.

Accepted for publication in Applied Physics Letters

References in corpus (4)

• Topological Surface States Protected From Backscattering by Chiral Spin Texture
• Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide
• Epitaxial growth of topological insulator Bi2Se3 film on Si(111) with atomically sharp interface
• Electronic Structures and Surface States of Topological Insulator Bi${}_{1-x}$Sb${}_x$

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• From classical to quantum regime of topological surface states via defect engineering
• An ab initio investigation of Bi${}_2$Se${}_3$ topological insulator deposited on amorphous SiO${}_2$