Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 12: Quantum Transport and Quantum Hall Effects (joint session HL/TT)
HL 12.5: Talk
Monday, March 17, 2025, 17:45–18:00, H15
Surface state dominated transport in HgTe topological insulator devices — •Maximilian Hofer1,2, Christopher Fuchs1,2, Lena Fürst1,2, Tobias Kießling1,2, Wouter Beugeling1,2, Hartmut Buhmann1,2, and Laurens W. Molenkamp1,2 — 1Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — 2Institute for Topological Insulators, Am Hubland, 97074 Würzburg, Germany
Recently grown three dimensional topological insulators based on tensile strained HgTe exhibit an exceptionally high mobility and very low intrinsic carrier density. The high quality material has made it possible to study the Landau level dispersion at low magnetic fields and identify four distinct transport regimes. We demonstrate that while a contribution from the topological surface states to transport measurements is expected across the full experimentally accessible density range, there exists only a narrow density regime for which the electronic transport is exclusively carried by the topological surface states. We present the corresponding phase diagram for pure topological surface state transport depending on layer thickness and carrier concentration. For thick HgTe films grown pseudomorphically strained on CdTe, the total carrier density needs to be kept between 1.8× 1011 cm−2 and 2.6× 1011 cm−2 to remain in the pure surface state region and avoid contributions from bulk states. The experimental observations are supported by eight band k·p band structure calculations.
Keywords: Topological insulators; Quantum transport; k.p theory; Zincblende semiconductor devices; HgCdTe