Differentiation of Surface and Bulk Conductivities in Topological Insulators via Four-Probe Spectroscopy

Durand, Corentin; Zhang, X.-G.; Hus, Saban M.; Ma, Chuanxu; McGuire, Michael A.; Yang, Xu; Cao, Helin; Miotkowski, I.; Chen, Yong P.; Li, An‐Ping

doi:10.1021/acs.nanolett.5b04425

Cited by 44 publications

(58 citation statements)

References 40 publications

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“…In this section, we examine the robustness of these NDR characteristics against changes in the multi-segment structure. [45,46] In this case, the interface states in the STM tip junction would be significantly different from our designed graphene/HS interfaces. In Figure 6 Figure 6c).…”

Section: Discussionmentioning

confidence: 88%

Design of Atomically Precise Nanoscale Negative Differential Resistance Devices

Xiao

Huang

et al. 2018

Advcd Theory and Sims

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Downscaling device dimensions to the nanometer range raises significant challenges to traditional device design, due to potential current leakage across nanoscale dimensions and the need to maintain reproducibility while dealing with atomic-scale components. Here, negative differential resistance (NDR) devices based on atomically precise graphene nanoribbons are investigated. The computational evaluation of the traditional double-barrier resonant-tunneling diode NDR structure uncovers important issues at the atomic scale, concerning the need to minimize the tunneling current between the leads while achieving high peak current. A new device structure consisting of multiple short segments that enables high current by the alignment of electronic levels across the segments while enlarging the tunneling distance between the leads is proposed. The proposed structure can be built with atomic precision using a scanning tunneling microscope (STM) tip during an intermediate stage in the synthesis of an armchair nanoribbon. An experimental evaluation of the band alignment at the interfaces and an STM image of the fabricated active part of the device are also presented. This combined theoretical-experimental approach opens a new avenue for the design of nanoscale devices with atomic precision.

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Section: Discussionmentioning

confidence: 88%

Design of Atomically Precise Nanoscale Negative Differential Resistance Devices

Xiao

Huang

et al. 2018

Advcd Theory and Sims

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“…Compared with the total conductance of the entire TI film, this results in an estimated amount of of the total current through the TI film to be transmitted by the TSS channel at the sample surface. The remaining part of the current we expect to be transmitted by the TSS channel at the substrate interface along with possible bulk contributions111219.…”

Section: Resultsmentioning

confidence: 99%

Electrical resistance of individual defects at a topological insulator surface

et al. 2017

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Three-dimensional topological insulators host surface states with linear dispersion, which manifest as a Dirac cone. Nanoscale transport measurements provide direct access to the transport properties of the Dirac cone in real space and allow the detailed investigation of charge carrier scattering. Here we use scanning tunnelling potentiometry to analyse the resistance of different kinds of defects at the surface of a (Bi0.53Sb0.47)2Te3 topological insulator thin film. We find the largest localized voltage drop to be located at domain boundaries in the topological insulator film, with a resistivity about four times higher than that of a step edge. Furthermore, we resolve resistivity dipoles located around nanoscale voids in the sample surface. The influence of such defects on the resistance of the topological surface state is analysed by means of a resistor network model. The effect resulting from the voids is found to be small compared with the other defects.

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“…The crucial advantage of the present study is the possibility to grow and characterize samples without breaking the vacuum. This is important because sample processing under ambient conditions, such as lithography, is reported to alter the electronic properties of TI samples 10,[16][17][18][19][20] and thus, the results of in situ photoemission measurements and ex situ transport measurements cannot be directly compared. In contrast, our seamless in situ approach allows a direct comparison of the respective results and enables the comprehensive analysis of our gate-dependent transport data.…”

Section: Transport Measurementsmentioning

confidence: 99%

In situ disentangling surface state transport channels of a topological insulator thin film by gating

et al. 2018

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In the thin film limit, the surface state of a three-dimensional topological insulator gives rise to two parallel conduction channels at the top and bottom surface of the film, which are difficult to disentangle in transport experiments. Here, we present gatedependent multi-tip scanning tunneling microscope transport measurements combined with photoemission experiments all performed in situ on pristine BiSbTe 3 thin films. To analyze the data, we develop a generic transport model including quantum capacitance effects. This approach allows us to quantify the gate-dependent conductivities, charge carrier concentrations, and mobilities for all relevant transport channels of three-dimensional topological insulator thin films (i.e., the two topological surface state channels, as well as the interior of the film). For the present sample, we find that the conductivity in the bottom surface state channel is minimized below a gate voltage of V gate = −34 V and the top surface state channel dominates the transport through the film.

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Differentiation of Surface and Bulk Conductivities in Topological Insulators via Four-Probe Spectroscopy

Cited by 44 publications

References 40 publications

Design of Atomically Precise Nanoscale Negative Differential Resistance Devices

Design of Atomically Precise Nanoscale Negative Differential Resistance Devices

Electrical resistance of individual defects at a topological insulator surface

In situ disentangling surface state transport channels of a topological insulator thin film by gating

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