Mid-Infrared Nano-Tomography Of Topological Insulator Surfaces
2019 44TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ)(2019)
摘要
We retrieve the local dielectric function of a few-nanometer-thick surface layer on the three-dimensional topological insulator (Bi0.5Sb0.5)(2)Te-3 using mid-infrared nano-tomography. Thereby, we identify the contributions of two types of surface states: Band bending leads to an intersubband transition within a massive two-dimensional electron gas, which gives rise to a sharp resonance. Conversely, an additional broadband absorption background may be caused by the topologically protected surface states. Tracing the dielectric response across a nanostructure reveals local changes to the resonance frequency of the intersubband transition, pointing towards nanoscale fluctuations of the doping or the Bi-to-Sb-ratio.
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关键词
topological insulator surfaces,local dielectric function,fewnanometer-thick surface layer,three-dimensional topological insulator,mid-infrared nanotomography,band bending,intersubband transition,two-dimensional electron gas,sharp resonance,topologically protected surface states,dielectric response,resonance frequency,additional broadband absorption background,nanostructure,nanoscale fluctuations,bismuth-antimony doping ratio,Bi0.5Sb0.5Te3
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