Epitaxial Growth and Characterizations of Topological P-N Junction in Sb2Te3/Bi2Te3 Heterostructures

Abstract

Bi2Te3 and Sb2Te3 topological insulator thin films have been successfully grown on Al2O3 (0001) substrates by molecular beam epitaxy (MBE) In-situ reflection high energy electron diffraction (RHEED) and ex-situ atomic force microscopy (AFM) indicate the smooth surface of the thin films Single crystalline structure of both Bi2Te3 and Sb2Te3 films are presented in XRD spectra The optimal growth condition for Bi2Te3 (Sb2Te3) is that the substrate nominally set at 310 ℃ (275 ℃) with beam flux ratio Bi:Te ~ 1:10 (Sb:Te ~ 1:17) At last the surface state of Bi2Te3 and Sb2Te3 thin films via ARPES reveals that they are indeed topological insulators After obtaining the growth conditions of Bi2Te3 and Sb2Te3 single layer we fabricated Sb2Te3/ Bi2Te3 bilayer on Al2O3 (0001) substrates and transferred a Hall bar pattern onto the films by photolithography Electrical transport properties illustrate the transition of carrier transport behavior with varying the thickness of Sb2Te3 upper layer We can assert that such method of regulating the thickness of bilayer topological insulator to tune the Dirac point to a desired energetic position will play an important role in the near future

Date of Award	2018 Aug 21
Original language	English
Supervisor	Jung-Chun Huang (Supervisor)