Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 39: Posters II (Topological insulators; Graphene; Spintronics and spin physics; Quantum information science)

HL 39.8: Poster

Tuesday, March 17, 2015, 14:00–20:00, Poster F

Fabrication and characterization of InAs/GaSb compound quantum wells for electrically tunable topological insulator devices — •Georg Knebl, Pierre Pfeffer, and Martin Kamp — Technische Physik, Universität Würzburg, Deutschland

InAs/GaSb compound quantum wells (CQW) sandwiched between two AlSb barrier layers were proposed by Liu et al. [1] to show a topological phase similar to the one realized in HgTe/CdTe [2]. While in the HgTe/CdTe system the transition from the normal to the topical insulator state can only be tuned by a variation of the quantum well thickness, for InAs/GaSb CQWs this is predicted to be tunable by the gate voltage. Our structures are fabricated by molecular beam epitaxy on GaSb and GaAs substrates, with an additional buffer structure on the latter ones. We will present results on the growth and fabrication of gated CQW structures for quantum spin Hall field effect transistors. Transport data and reversible light induced switching of majority carriers from electrons to holes will be shown.

[1] C. Liu, T. Hughes, X.-L. Qi, K. Wang, and S.-C. Zhang, Quantum Spin Hall Effect in Inverted Type-II Semiconductors, Phys. Rev. Lett., vol. 100, no. 23, p. 236601, Jun. 2008.

[2] M. König, S. Wiedmann, C. Brüne, A. Roth, H. Buhmann, L. W. Molenkamp, X.-L. Qi, and S.-C. Zhang, Quantum spin hall insulator state in HgTe quantum wells., Science, vol. 318, no. 5851, pp. 766-70, Nov. 2007.