Differentiation of Surface and Bulk Conductivities in Topological Insulators via Four-Probe Spectroscopy

详细信息    查看全文

• 作者：Corentin Durand ; X.-G. Zhang ; Saban M. Hus ; Chuanxu Ma ; Michael A. McGuire ; Yang Xu ; Helin Cao ; Ireneusz Miotkowski ; Yong P. Chen ; An-Ping Li
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：16
• 期：4
• 页码：2213-2220
• 全文大小：437K
• 年卷期：0
• ISSN：1530-6992

文摘

We show a new method to differentiate conductivities from the surface states and the coexisting bulk states in topological insulators using a four-probe transport spectroscopy in a multiprobe scanning tunneling microscopy system. We derive a scaling relation of measured resistance with respect to varying interprobe spacing for two interconnected conduction channels to allow quantitative determination of conductivities from both channels. Using this method, we demonstrate the separation of 2D and 3D conduction in topological insulators by comparing the conductance scaling of Bi₂Se₃, Bi₂Te₂Se, and Sb-doped Bi₂Se₃ against a pure 2D conductance of graphene on SiC substrate. We also quantitatively show the effect of surface doping carriers on the 2D conductance enhancement in topological insulators. The method offers a means to understanding not just the topological insulators but also the 2D to 3D crossover of conductance in other complex systems.