RF compressibility of topological surface and interface states in metal-hBN-Bi2Se3 capacitors

Abstract

The topological state that emerges at the surface of a topological insulator (TI) and at the TI-substrate interface are studied in metal-hBN-Bi2Se3 capacitors. By measuring the RF admittance of the capacitors versus gate voltage, we extract the compressibility of the Dirac state located at a gated TI surface. We show that even in the presence of an ungated surface that hosts a trivial electron accumulation layer, the other gated surface always exhibits an ambipolar effect in the quantum capacitance. We succeed in determining the velocity of surface Dirac fermions in two devices, one with a passivated surface and the other with a free surface that hosts trivial states. Our results demonstrate the potential of RF quantum capacitance techniques to probe surface states of systems in the presence of a parasitic density-of-states.

arXiv commentJ. Phys.: Mater. Focus on Topological Matter

References in corpus (25)

• Boron nitride substrates for high-quality graphene electronics
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Discovery of a Weyl Fermion Semimetal and Topological Fermi Arcs
• Micrometer-scale ballistic transport in encapsulated graphene at room temperature
• Experimental observation of topological Fermi arcs in type-II Weyl semimetal MoTe2
• Electrically detected interferometry of Majorana fermions in a topological insulator
• An On-Demand Coherent Single Electron Source
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Bulk Fermi surface coexistence with Dirac surface state in Bi${}_2$Se${}_3$: a comparison of photoemission and Shubnikov-de Haas measurements
• Strong surface scattering in ultrahigh mobility Bi2Se3 topological insulator crystals
• Surface conduction of topological Dirac electrons in bulk insulating Bi2Se3
• Gapless Andreev bound states in the quantum spin Hall insulator HgTe
• Interaction phenomena in graphene seen through quantum capacitance
• Supercollision cooling in undoped graphene
• Controlling spin relaxation in hexagonal BN-encapsulated graphene with a transverse electric field
• Record Surface State Mobility and Quantum Hall Effect in Topological Insulator Thin Films via Interface Engineering
• Radio frequency electrical transduction of graphene mechanical resonators
• A graphene Zener-Klein transistor cooled by a hyperbolic substrate
• Magneto-optics of massive Dirac fermions in bulk Bi2Se3
• Single Carbon Nanotube Transistor at GHz Frequency
• Observation of Volkov-Pankratov states in topological HgTe heterojunctions using high-frequency compressibility
• Transport scattering time probed through rf admittance of a graphene capacitor
• Weak-link Josephson Junctions Made from Topological Crystalline Insulators
• Direct observation of decoupled Dirac states at the interface between topological and normal insulators
• Proximity-induced superconductivity and quantum interference in topological crystalline insulator SnTe thin film devices