Manipulating InAs nanowires with submicrometer precision

Flöhr, Kilian; Liebmann, Marcus; Sladek, Kamil; Günel, H. Yusuf; Frielinghaus, Robert; Haas, Fabian; Meyer, Carola; Hardtdegen, H.; Schäpers, Thomas; Grützmacher, Detlev; Morgenstern, Markus

doi:10.1063/1.3657135

Cited by 36 publications

(26 citation statements)

References 33 publications

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“…Fig. 3 displays the diameter dependence of the thermal conductivity of Bi NWs, measured using the suspended microdevice (inset) at room temperature, with five different diameters 40,69,203,230, and 301 nm. The previous thermal conductivity data, obtained using single-crystalline Bi NWs grown by same method (OFFON) 23 and AAO templates, 38 confirm the reliability of the measurements.…”

Section: Seebeck Coefficientmentioning

confidence: 99%

“…A Bi NW with such a small diameter (d < 40 nm) could not sustain when placed between the two membranes of the suspended microdevice, and a few dispersed Bi NWs were cracked during the drop casting. To place a selected Bi NW of such a diameter on the suspended microdevice, a nano-manipulator system 40,41 is preferred instead of the drop-casting method, in which the membranes were bent by the dropped solution.…”

Section: Seebeck Coefficientmentioning

confidence: 99%

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Diameter-dependent thermoelectric figure of merit in single-crystalline Bi nanowires

et al. 2015

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The diameter-dependent thermoelectric properties of individual single-crystalline Bi nanowires grown by the on-film formation of nanowires method have been investigated. The electrical resistivity, Seebeck coefficient, and thermal conductivity were measured as functions of the nanowire diameter using an individual nanowire device. The thermoelectric figure of merit (ZT ) calculated from the measured thermoelectric properties shows an increase from the bulk value to a maximum value of 0.28 at 109 nmdiameter, followed by a decrease upon further decreasing the diameter. This non-monotonic diameter dependence of ZT in Bi nanowires reveals simultaneous positive and negative contributions to the thermoelectric efficiency, driven by the change in intrinsic properties, which originates from the diameter-dependent classical and quantum size effects.

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Section: Seebeck Coefficientmentioning

confidence: 99%

Section: Seebeck Coefficientmentioning

confidence: 99%

Diameter-dependent thermoelectric figure of merit in single-crystalline Bi nanowires

et al. 2015

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“…The gates are covered by a 10 nm layer of HfO 2 dielectric. Using a micromanipulator 28 the nanowires with a typical length of 4 µm and diameter of 30 nm are placed on top of these gates as shown in the inset of Fig. 1.…”

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confidence: 99%

Magnetic field evolution of spin blockade in Ge/Si nanowire double quantum dots

Zarassi

Danon

et al. 2017

Phys. Rev. B

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We perform transport measurements on double quantum dots defined in Ge/Si core/shell nanowires and focus on Pauli spin blockade in the regime where tens of holes occupy each dot. We identify spin blockade through the magnetic field dependence of leakage current. We find both a dip and a peak in the leakage current at zero field. We analyze this behavior in terms of the quantum dot parameters such as coupling to the leads, interdot tunnel coupling as well as spin-orbit interaction. We find a lower bound for spin-orbit interaction with lso = 500 nm. We also extract large and anisotropic effective Landé g-factors, with larger g-factors in the direction perpendicular to the nanowire axis in agreement with previous studies and experiments but with larger values reported here.Studies of spin blockade in quantum dots are largely motivated by the proposals to build a spin-based quantum computer 1 , as spin blockade can be used for qubit initialization and readout 2,3 . At the same time, spin blockade and its lifting mechanisms offer a direct insight into spin relaxation and dephasing processes in semiconductors and provide deeper understanding of interactions between spin localized in a quantum dot and its environment, be it the lattice and its vibrations or nuclear spins, spin-orbit interaction, or coupling to spins in nearby dots or in the lead reservoirs 4-8 .Holes in Ge/Si nanowires offer a relatively unexplored platform for such studies 9 . On the one hand, hyperfine interaction is expected to be greatly reduced owing to the low abundance of nonzero nuclear spin isotopes in the group IV materials 10 . Moreover, holes weakly couple to nuclear spins due to their p-wave Bloch wave symmetry, thus they are expected to come with longer spin relaxation times 11 . Heavy/light hole degeneracy may also influence the spin blockade regime 12 . On the other hand, spin-orbit interaction is predicted 13 and suggested by experiments 14-17 to be strong in Ge/Si core/shell nanowires. This offers a path to electrical spin manipulation 18,19 , as well as to realizing Majorana fermions [20][21][22][23] .In this work we perform transport measurements on electrostatically defined double quantum dots 2 made in Ge/Si core/shell nanowires, and detect Pauli spin blockade at several charge degeneracy points. We expand and adapt a previously developed rate equation model to analyze the magnetic-field evolution of the leakage current 24 . We also observe large and anisotropic g-factors in these dots, which supports recent theoretical predictions 25 and experimental observations 26,27 .The devices are fabricated on n-doped Si substrates covered with 500 nm of thermal SiO 2 and patterned with local gate arrays of Ti/Au stripes with center to center distance of 60 nm. The gates are covered by a 10 nm layer of HfO 2 dielectric. Using a micromanipulator 28 the nanowires with a typical length of 4 µm and diameter of 30 nm are placed on top of these gates as shown in the inset of Fig. 1. After wet etching with buffered hydrofluoric acid, we sputter 15...

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“…The chemical stability, atomic flatness, and high breakdown voltage, 21 together with the well established dry transfer mechanism 22 makes hBN an ideal dielectric for our nanowire devices. InSb nanowires grown by metal-organic vapor phase epitaxy 23,24 (1 -3µm long and 70 -90nm diameter) are transferred deterministically with a micro-manipulator 25 onto the hBN dielectric. Electrical contacts to the nanowire (evaporated Cr/Au (10/100 nm), 150 -400nm spacing) are defined by electron beam lithography.…”

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confidence: 99%

Conductance Quantization at Zero Magnetic Field in InSb Nanowires

et al. 2016

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Ballistic electron transport is a key requirement for existence of a topological phase transition in proximitized InSb nanowires. However, measurements of quantized conductance as direct evidence of ballistic transport have so far been obscured due to the increased chance of backscattering in one dimensional nanowires. We show that by improving the nanowiremetal interface as well as the dielectric environment we can consistently achieve conductance quantization at zero magnetic field. Additionally, studying the sub-band evolution in a rotating magnetic field reveals an orbital degeneracy between the second and third sub-bands for perpendicular fields above 1 T.

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Manipulating InAs nanowires with submicrometer precision

Cited by 36 publications

References 33 publications

Diameter-dependent thermoelectric figure of merit in single-crystalline Bi nanowires

Diameter-dependent thermoelectric figure of merit in single-crystalline Bi nanowires

Magnetic field evolution of spin blockade in Ge/Si nanowire double quantum dots

Conductance Quantization at Zero Magnetic Field in InSb Nanowires

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