Scanning tunneling potentiometry implemented into a multi-tip setup by software

Lüpke, Felix; Korte, Stefan; Cherepanov, Vasily; Voigtländer, Bert

doi:10.1063/1.4936079

Cited by 24 publications

(47 citation statements)

References 19 publications

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“…For this purpose, the amount of current through the tip at a certain tip bias voltage V bias is read into the measurement software via an ADC converter and the feedback loop nulls the tip-sample current by continuously adjusting V bias via a digital-toanalog converter (DAC) connected to the V bias input of that tip, until V bias = V local [11,15].…”

Section: (B) the Voltage Sensing Is Performedmentioning

confidence: 99%

“…The switching between the two measurement modes is then performed e.g. by a relay [8,11]. A drawback of this approach is, that it leads to bulky, complex electronics and introduces additional noise to the measurements due to the additional circuitry.…”

Section: Introductionmentioning

confidence: 99%

“…An alternative way to measure local sample potentials in a STM is the scanning tunneling potentiometry method [11,14,15]. In this method, the voltage applied to the tip is controlled by a feedback loop, such that the current to the sample vanishes, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, in order to approach the tips to the sample surface and to exchange contacts during four-probe measurements, the tips have to be rewired to the different electronics in between measurements. One approach to simplify this process is to use four instances of identical electronics which can perform both, voltage and current measurements [8,11] as shown in Fig. 1 (left).…”

Section: Introductionmentioning

confidence: 99%

“…Originally proposed by F. Wenner for application in geophysics [2], today fourprobe measurements can be found in a wide range of applications including semiconductor characterization [1]. Due to their high accuracy, four-probe measurements are often used in fundamental research such as (low temperature) transport measurements where the sample under investigation is typically contacted by lithographic contacts [3], monolithic four-point probes [4][5][6][7] or a multi-tip scanning tunneling microscope (STM) [8][9][10][11][12][13]. In general, the four-probe measurement setup consists of two biased contacts which inject a current into the sample and two contacts which measure the resulting voltage drop across the sample, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Four-point probe measurements using current probes with voltage feedback to measure electric potentials

Lüpke

Cuma

Korte

et al. 2018

J. Phys.: Condens. Matter

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We present a four-point probe resistance measurement technique which uses four equivalent current measuring units, resulting in minimal hardware requirements and corresponding sources of noise. Local sample potentials are measured by a software feedback loop which adjusts the corresponding tip voltage such that no current flows to the sample. The resulting tip voltage is then equivalent to the sample potential at the tip position. We implement this measurement method into a multi-tip scanning tunneling microscope setup such that potentials can also be measured in tunneling contact, allowing in principle truly non-invasive four-probe measurements.The resulting measurement capabilities are demonstrated for BiSbTe 3 and Si(111)−(7×7) samples.

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Section: (B) the Voltage Sensing Is Performedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Four-point probe measurements using current probes with voltage feedback to measure electric potentials

Lüpke

Cuma

Korte

et al. 2018

J. Phys.: Condens. Matter

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Electronic Transport Properties of 1D‐Defects in Graphene and Other 2D‐Systems

2017

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The continuous progress in device miniaturization demands a thorough understanding of the electron transport processes involved. The influence of defects -discontinuities in the perfect and translational invariant crystal lattice -plays a crucial role here. For graphene in particular, they limit the carrier mobility often demanded for applications by contributing additional sources of scattering to the sample. Due to its two-dimensional nature graphene serves as an ideal system to study electron transport in the presence of defects, because one-dimensional defects like steps, grain boundaries and interfaces are easy to characterize and have profound effects on the transport properties. While their contribution to the resistance of a sample can be extracted by carefully conducted transport experiments, scanning probe methods are excellent tools to study the influence of defects locally. In this letter, the authors review the results of scattering at local defects in graphene and other 2D systems by scanning tunneling potentiometry, 4-point-probe microscopy, Kelvin probe force microscopy and conventional transport measurements. Besides the comparison of the different defect resistances important for device fabrication, the underlying scattering mechanisms are discussed giving insight into the general physics of electron scattering at defects.

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Strong and Weak 3D Topological Insulators Probed by Surface Science Methods

Morgenstern

Pauly

Kellner

et al. 2020

Physica Status Solidi (b)

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We review the contributions of surface science methods to discover and improve 3D topological insulator materials, while illustrating with examples from our own work. In particular, we demonstrate that spin-polarized angularresolved photoelectron spectroscopy is instrumental to evidence the spin-helical surface Dirac cone, to tune its Dirac point energy towards the Fermi level, and to discover novel types of topological insulators such as dual ones or switchable ones in phase change materials. Moreover, we introduce procedures to spatially map potential fluctuations by scanning tunneling spectroscopy and to identify topological edge states in weak topological insulators. I. INTRODUCTIONTopology became a classification scheme for solid state electronic properties in the 1980s while describing the robustness of the quantum Hall effect [1,2]. This achievement has been honored most notably by the Noble prize 2016 for physics [3,4]. The well-deserved appreciation was largely triggered by the experimental discovery of 2D topological insulators (2DTIs) in 2007 [5]. This discovery initiated a major effort in experimental and theoretical solid state physics leading to a multitude of other types of topologies in crystalline solids, mostly appearing without magnetic fields [6][7][8]. The overwhelming success has also led to activities in other fields of physics enabling, e.g., the guiding of light or sound along arbitrarily shaped edges [9][10][11][12]. The attractive robustness of the topological properties, tied to the integer character of the topological indices, implied a multitude of proposals also for electronic applications [13][14][15]. This currently culminates in the actively pursued dream to realize topological quantum computation via parafermions [16][17][18][19]. The central advantage of this approach is the robustness of corresponding quantum operations against local perturbations as long as the quasiparticles remain in their topologically protected subspace.From the point of view of materials science, the intriguing observation that a lot of wellknown materials are three-dimensional strong topological insulators added a crucial view on electronic band structure properties [6][7][8]. It turned out that a large amount of bulk insulators necessarily provide spin helical conductive surface states [20,21] via the symmetry of their bulk band structure described by a topological index [22,23]. The presence of such 2 surface states is totally independent on details of the confining surfaces and, moreover, these surface states are protected against backscattering by their spin helicity [6,24]. Hence, such materials can be thought of as a third conductivity class besides conductors and insulators, being insulating in the interior of the system but conducting on its surfaces. Favorably, a simple classification scheme exists in case of inversion symmetry of the crystal [24]. It simply multiplies the parities (point inversion symmetries) of occupied single-electron states at the time-reversal invariant momenta (TRIMs) of ...

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Scanning tunneling potentiometry implemented into a multi-tip setup by software

Cited by 24 publications

References 19 publications

Four-point probe measurements using current probes with voltage feedback to measure electric potentials

Four-point probe measurements using current probes with voltage feedback to measure electric potentials

Electronic Transport Properties of 1D‐Defects in Graphene and Other 2D‐Systems

Strong and Weak 3D Topological Insulators Probed by Surface Science Methods

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