Low-Temperature Scanning Tunneling Microscopy of Ring-Like Surface Electronic Structures Around Co Islands on InAs(110) Surfaces

Muzychenko, D. A.; Schouteden, Koen; Savinov, S. Yu.; Maslova, N. S.; Panov, V. I.; Haesendonck, C. Van

doi:10.1166/jnn.2009.1086

Cited by 4 publications

(6 citation statements)

References 24 publications

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“…At energies below the semiconducting gap (i.e. at E < −100 meV) these peaks show negative differential conductance (highlighted in red) [24]. We have detected similar phenomena at the vicinity of the polycrystalline gold droplet at the end of the InAs nanowire that catalyzed its growth (see Appendix C for more details).…”

Section: A Fermi Level Pinning In Inas Nanowiressupporting

confidence: 57%

Spectroscopic Visualization of a Robust Electronic Response of Semiconducting Nanowires to Deposition of Superconducting Islands

et al. 2020

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Following significant progress in the visualization and characterization of Majorana end modes in hybrid systems of semiconducting nanowires and superconducting islands, much attention is devoted to the investigation of the electronic structure at the buried interface between the semiconductor and the superconductor. The properties of that interface and the structure of the electronic wavefunctions that occupy it determine the functionality and the topological nature of the superconducting state induced therein. Here we study this buried interface by performing spectroscopic mappings of superconducting aluminum islands epitaxially grown in-situ on indium arsenide nanowires. We find unexpected robustness of the hybrid system as the direct contact with the aluminum islands does not lead to any change in the chemical potential of the nanowires, nor does it induce a significant band bending in their vicinity. We attribute this to the presence of surface states bound to the facets of the nanowire. Such surface states, that are present also in bare nanowires prior to aluminum deposition, pin the Fermi-level thus rendering the nanowires resilient to surface perturbations. The aluminum islands further display Coulomb blockade gaps and peaks that signify the formation of a resistive tunneling barrier at the InAs-Al interface. The extracted interface resistivity, ρ ≈ 1.3 × 10 −6 Ω cm 2 , will allow to proximity-induce superconductivity with negligible Coulomb blockade effects by islands with interface area as small as 0.01 µm 2 . At low energies we identify a potential energy barrier that further suppresses the transmittance through the interface. A corresponding barrier exists in bare semiconductors between surface states and the accumulation layer, induced to maintain charge neutrality. Our observations elucidate the delicate interplay between the resistive nature of the InAs-Al interface and the ability to proximitize superconductivity and tune the chemical potential in semiconductor-superconductor hybrid nanowires.

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Section: A Fermi Level Pinning In Inas Nanowiressupporting

confidence: 57%

Spectroscopic Visualization of a Robust Electronic Response of Semiconducting Nanowires to Deposition of Superconducting Islands

et al. 2020

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“…Most of rings appear bright at positive sample voltages and dark at negative sample voltages. A similar behavior has been reported in paper 24 (see also paper 29 ), where Co islands on InAs surfaces have been studied. In Co/InAs, E s F is also above conduction band minimum, in analogy with our samples, so it is natural to assume that this feature plays an important role in changing rings contrast.…”

supporting

confidence: 85%

“…Charged individual Fe-impurities embedded in Bi 2 Se 3 have already been reported in previous works 15,17,18 and produce ring-shaped spectral features in conductance images of scanning tunneling microscopy experiments. Also, the observation of impurity charging is not exclusive to TIs: ionization rings were observed near defects in several materials such as semiconductors [19][20][21][22] , graphene 23 and semiconductor surfaces with deposited Co-islands 24 . In our work, we show that the position of the Fermi energy with respect to the Dirac point and the bulk bands 25 plays a crucial role in the charge screening and scattering in TIs.…”

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confidence: 99%

Double Fe-impurity charge state in the topological insulator Bi2Se3

Stolyarov

Remizov

Shapiro

et al. 2017

Applied Physics Letters

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The influence of individual impurities of Fe on the electronic properties of topological insulator Bi 2 Se 3 is studied by Scanning Tunneling Microscopy. The microscope tip is used in order to remotely charge/discharge Fe impurities. The charging process is shown to depend on the impurity location in the crystallographic unit cell, on the presence of other Fe impurities in the close vicinity, as well as on the overall doping level of the crystal. We present a qualitative explanation of the observed phenomena in terms of tip-induced local band bending. Our observations evidence that the specific impurity neighborhood and the position of the Fermi energy with respect to the Dirac point and bulk bands have both to be taken into account when considering the electron scattering on the disorder in topological insulators. arXiv:1712.00915v2 [cond-mat.mes-hall]

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“…Thus, the dielectric thickness d = 4 nm extracted from C sub above is actually set by the Debye length of the 2D gas and C sub actually corresponds to the quantum capacitance of InAs. Finally, a survey of the literature shows that Coulomb blockade has already been observed in metallic clusters deposited on InAs 41,42,74 . The nature of the tunnel barrier was not identified in those works, though.…”

Section: E Nature Of the Tunnel Barriermentioning

confidence: 94%

“…island mode 29 . Island growth of metals evaporated on III-V semiconductor has been observed for various elements on GaAs such as Ag [37][38][39][40] , Au 32 , Fe 34 as well as metals on InAs such as Co 41,42 .…”

Section: Introductionmentioning

confidence: 99%

Quantum confinement effects in Pb nanocrystals grown on InAs

et al. 2018

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In the recent work of Ref. 1 , it has been shown that Pb nanocrystals grown on the electron accumulation layer at the (110) surface of InAs are in the regime of Coulomb blockade. This enabled the first scanning tunneling spectroscopy study of the superconducting parity effect across the Anderson limit. The nature of the tunnel barrier between the nanocrystals and the substrate has been attributed to a quantum constriction of the electronic wave-function at the interface due to the large Fermi wavelength of the electron accumulation layer in InAs. In this manuscript, we detail and review the arguments leading to this conclusion. Furthermore, we show that, thanks to this highly clean tunnel barrier, this system is remarkably suited for the study of discrete electronic levels induced by quantum confinement effects in the Pb nanocrystals. We identified three distinct regimes of quantum confinement. For the largest nanocrystals, quantum confinement effects appear through the formation of quantum well states regularly organized in energy and in space. For the smallest nanocrystals, only atomic-like electronic levels separated by a large energy scale are observed. Finally, in the intermediate size regime, discrete electronic levels associated to electronic wave-functions with a random spatial structure are observed, as expected from Random Matrix Theory.arXiv:1810.08925v1 [cond-mat.supr-con]

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Low-Temperature Scanning Tunneling Microscopy of Ring-Like Surface Electronic Structures Around Co Islands on InAs(110) Surfaces

Cited by 4 publications

References 24 publications

Spectroscopic Visualization of a Robust Electronic Response of Semiconducting Nanowires to Deposition of Superconducting Islands

Spectroscopic Visualization of a Robust Electronic Response of Semiconducting Nanowires to Deposition of Superconducting Islands

Double Fe-impurity charge state in the topological insulator Bi2Se3

Quantum confinement effects in Pb nanocrystals grown on InAs

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