Influence of surface band bending on a narrow band gap semiconductor: Tunneling atomic force studies of graphite with Bernal and rhombohedral stacking orders

Abstract

Tunneling atomic force microscopy (TUNA) was used at ambient conditions to measure the current-voltage ($I$-$V$) characteristics at clean surfaces of highly oriented graphite samples with Bernal and rhombohedral stacking orders. The characteristic curves measured on Bernal-stacked graphite surfaces can be understood with an ordinary self-consistent semiconductor modeling and quantum mechanical tunneling current derivations. We show that the absence of a voltage region without measurable current in the $I$-$V$ spectra is not a proof of the lack of an energy band gap. It can be induced by a surface band bending due to a finite contact potential between tip and sample surface. Taking this into account in the model, we succeed to obtain a quantitative agreement between simulated and measured tunnel spectra for band gaps $(12\dots 37)$\,meV, in agreement to those extracted from the exponential temperature decrease of the longitudinal resistance measured in graphite samples with Bernal stacking order. In contrast, the surface of relatively thick graphite samples with rhombohedral stacking reveals the existence of a maximum in the first derivative $dI/dV$, a behavior compatible with the existence of a flat band. The characteristics of this maximum are comparable to those obtained at low temperatures with similar techniques.

12 pages, 10 figures

References in corpus (13)

• Electrostatic Force Microscopy on Oriented Graphite Surfaces: Where Insulating and Conducting Behaviors Coexist
• Evidence of Josephson-coupled superconducting regions at the interfaces of Highly Oriented Pyrolytic Graphite
• A consistent interpretation of the low temperature magneto-transport in graphite using the Slonczewski--Weiss--McClure 3D band structure calculations
• Magnetic gap opening in rhombohedral-stacked multilayer graphene from first principles
• Identification of a possible superconducting transition above room temperature in natural graphite crystals
• Two topologically distinct Dirac-line semimetal phases and topological phase transitions in rhombohedrally stacked honeycomb lattices
• Direct Probing Stacking Order and Electronic Spectrum of Rhombohedral Trilayer Graphene with Scanning Tunneling Microscopy
• Integer Quantum Hall Effect in Graphite
• The Raman fingerprint of rhombohedral graphite
• Evidence for room temperature superconductivity at graphite interfaces
• Granular superconductivity below 5~K in SPI-II pyrolytic graphite
• Anomalous Hall Effect in Graphite
• Nonintrinsic origin of the magnetic-field-induced metal-insulator and electronic phase transitions in graphite

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