Van der Waals epitaxial growth of topological insulator Bi$_{2-x}$Sb$_x$Te$_{3-y}$Se$_y$ ultrathin nanoplate on electrically insulating fluorophlogopite mica

TL;DR

This paper demonstrates the van der Waals epitaxial growth of high-quality BiSbTeSe ultrathin nanoplates on insulating mica, enabling controlled composition and thickness, with robust surface Dirac cone transport suitable for topological insulator applications.

Contribution

It introduces a catalyst-free vapor solid method for growing high-quality BSTS nanoplates on mica with precise control over their properties.

Findings

Successful growth of BSTS nanoplates on mica.

Raman spectra confirm controlled composition and thickness.

Electrical measurements show robust Dirac cone surface transport.

Abstract

We report the growth of high quality Bi$_{2-x}$Sb$_x$Te$_{3-y}$Se$_y$ ultrathin nanoplates (BSTS-NPs) on an electrically insulating fluorophlogopite mica substrate using a catalyst-free vapor solid method. Under an optimized pressure and suitable Ar gas flow rate, we control the thickness, the size and the composition of BSTS-NPs. Raman spectra showing systematic change indicate that the thicknesses and compositions of BSTS-NPs are indeed accurately controlled. Electrical transport demonstrates that a robust Dirac cone carrier transport in BSTS-NPs. Since BSTS-NPs provide superior dominant surface transport of the tunable Dirac cone surface states with negligible contribution of the conduction of the bulk states, BSTS-NPs provide an ideal platform to explore intrinsic physical phenomena as well as technological applications of 3-dimensional topological insulators in the future.