Van der Waals epitaxial growth of topological insulator Bi _2-xSb_xTe_3-ySe_y ultrathin nanoplate on electrically insulating fluorophlogopite mica

We report the growth of high quality Bi_2-xSb _xTe_3-ySe_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 the BSTS-NPs. Raman spectra showing systematic change indicate that the thicknesses and compositions of the BSTS-NPs are indeed accurately controlled. Electrical transport demonstrates a robust Dirac cone carrier transport in the BSTS-NPs. Since the BSTS-NPs provide superior dominant surface transport of the tunable Dirac cone surface states with negligible contribution of the conduction of the bulk states, the BSTS-NPs provide an ideal platform to explore intrinsic physical phenomena as well as technological applications of 3-dimensional topological insulators in the future.