Robust Topological Interfaces and Charge Transfer in Epitaxial Bi2Se3/II鈥揤I Semiconductor Superlattices

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• 作者：Zhiyi Chen ; Lukas Zhao ; Kyungwha Park ; Thor Axtmann Garcia ; Maria C. Tamargo ; Lia Krusin-Elbaum
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：October 14, 2015
• 年：2015
• 卷：15
• 期：10
• 页码：6365-6370
• 全文大小：465K
• ISSN：1530-6992

文摘

Access to charge transport through Dirac surface states in topological insulators (TIs) can be challenging due to their intermixing with bulk states or nontopological two-dimensional electron gas (2DEG) quantum well states caused by bending of electronic bands near the surface. The band bending arises via charge transfer from surface adatoms or interfaces and, therefore, the choice of layers abutting topological surfaces is critical. Here we report molecular beam epitaxial growth of Bi₂Se₃/Zn_xCd_1鈥?i>xSe superlattices that hold only one topological surface channel per TI layer. The topological nature of conducting channels is supported by 蟺-Berry phase evident from observed Shubnikov de Haas quantum oscillations and by the associated two-dimensional (2D) weak antilocalization quantum interference correction to magnetoresistance. Both density functional theory (DFT) calculations and transport measurements suggest that a single topological Dirac cone per TI layer can be realized by asymmetric interfaces: Se-terminated Zn_xCd_1鈥?i>xSe interface with the TI remains 鈥渆lectronically intact鈥? while charge transfer occurs at the Zn-terminated interface. Our findings indicate that topological transport could be controlled by adjusting charge transfer from nontopological spacers in hybrid structures.