Persistent Topological Surface State at the Interface of Bi2Se3 Film Grown on Patterned Graphene

TL;DR

This study demonstrates that graphene can serve as an effective template to preserve and observe topological surface states in Bi2Se3 films, enabling potential microelectronic applications without degrading the surface states.

Contribution

It shows that epitaxial Bi2Se3 films grown on patterned graphene maintain topological surface states with high mobility, facilitating interface engineering for device integration.

Findings

Topological surface states observed at the Bi2Se3/graphene interface.

Bi2Se3 grows epitaxially without interfacial strain.

Surface states remain intact with high mobility (~0.5 m^2/Vs).

Abstract

We employed graphene as a patternable template to protect the intrinsic surface states of thin films of topological insulators (TIs) from environment. Here we find that the graphene provides high-quality interface so that the Shubnikov de Haas (SdH) oscillation associated with a topological surface state could be observed at the interface of a metallic Bi2Se3 film with a carrier density higher than ~10^19 cm-3. Our in situ X-ray diffraction study shows that the Bi2Se3 film grows epitaxially in a quintuple layer-by-layer fashion from the bottom layer without any structural distortion by interfacial strain. The magnetotransport measurements including SdH oscillations stemming from multiple conductance channels reveal that the topological surface state, with the mobility as high as ~0.5 m^2/Vs, remains intact from the graphene underneath without degradation. Given that the graphene was prepatterned on arbitrary insulating substrates, the TI-based microelectronic design could be exploited. Our study thus provides a step forward to observe the topological surface states at the interface without degradation by tuning the interface between TI and graphene into a measurable current for device application.