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

摘要

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 fluorophlogopitemica substrate using a catalyst-free vapor solid method. Under an optimizedpressure and suitable Ar gas flow rate, we control the thickness, the size andthe composition of BSTS-NPs. Raman spectra showing systematic change indicatethat the thicknesses and compositions of BSTS-NPs are indeed accuratelycontrolled. Electrical transport demonstrates that a robust Dirac cone carriertransport in BSTS-NPs. Since BSTS-NPs provide superior dominant surfacetransport of the tunable Dirac cone surface states with negligible contributionof the conduction of the bulk states, BSTS-NPs provide an ideal platform toexplore intrinsic physical phenomena as well as technological applications of3-dimensional topological insulators in the future.