High-mobility electron systems in remotely-doped InSb quantum wells

Keywords: InSb quantum well, quantum point contact, g-factor anisotropy, electron effective mass, conductance quantization 2 Due to a strong spin-orbit interaction and a large Landé g-factor, InSb plays an important role in research on Majorana fermions. To further explore novel properties of Majorana fermions, hybrid devices based on quantum wells are conceived as an alternative approach to nanowires. In this work, we report a pronounced conductance quantization of quantum point contact devices in InSb/InAlSb quantum wells. Using a rotating magnetic field, we observe a large in-plane( 1 26 g  ) and out-of-plane ( 1 52 g  ) g-factor anisotropy. Additionally, we investigate crossings of subbands with opposite spins and extract the electron effective mass from magnetic depopulation of one-dimensional subbands.Among the binary III-V semiconductors, InSb has the smallest effective mass and the highest room temperature mobility 1 . It further exhibits a strong spin-orbit interaction (SOI) and the largest Landé g-factor ( 51 g  for the bulk), due to the strong coupling between the conduction band and the valence band resulting from the small energy gap [1][2][3] . Besides the continuously increasing interest in its various applications in spintronics 4 , InSb has been extensively investigated for Majorana fermions and topological quantum computing (TQC) 5,6 . Applying a magnetic field perpendicular to the spin-orbit field of a nanowire opens a Zeeman energy gap wells are yet to be established. In this work, we demonstrate ballistic transport through QPCs in an InSb 2DEG. In a rotating magnetic field, the Zeeman spin splitting is investigated and a large 4 in-plane and out-of-plane g-factor anisotropy is observed. Furthermore, crossings of subbands with opposite spins are studied and the electron effective mass is deduced using magnetic depopulation 34,35 .The InSb/InAlSb heterostructure used in this work is grown on a GaAs (100) By a comparison of the two types of QPCs, we find that the etch-defined QPC shows pronounced quantized conductance plateaus at zero magnetic field, while the fully gate-defined type requires a small perpendicular magnetic field to suppress backscattering and interference.Therefore, we focus on the former in the following and briefly present the results on the latter in the Supporting Information Fig. S1. At large Bz > 1 T (out-of-plane), as shown in Fig. 3a, in contrast to the case of Bx, all plateaus widen due to Zeeman splitting and magnetic depopulation of 1D subbands, as will be discussed below. For the case of By (in-plane but perpendicular to current flow), as displayed in Fig. 3b, the behavior is similar to that in Bx, although here the measured magnetic field range is smaller.To directly inspect the evolution of the spin splitting in a magnetic field along different orientations, the magnetic field is rotated in the x-z plane (Fig. 3c) and the x-y plane (Fig. 3d) 7 while keeping the amplitude fixed at 1.8 T and 1 T, respectively. The magnetoresistance from the adjacent InSb 2DEG i...

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“…The mobility can exceed 200,000 cm 2 /Vs [17][18][19] , corresponding to a mean free path larger than 1.4 µm. To realize 1D…”

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confidence: 99%

Quantized Conductance and Large g-Factor Anisotropy in InSb Quantum Point Contacts

Veen

Vries

et al. 2016

Nano Lett.

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“…Electron mobility greater than 100 000 cm 2 /V s and a corresponding electron mean-free path in the sub-micrometer range are achievable. Although InSb/InAlSb quantum wells (QWs) with two-dimensional electron gas (2DEG) mobility in excess of 200 000 cm 2 /V s have been developed, 8,9 they are often plagued with parallel conduction channels which may be difficult to deplete. Gate tunability of the 2DEG density to full depletion is needed in split-gate quantum structures.…”

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confidence: 99%

Gate-tunable high mobility remote-doped InSb/In1−xAlxSb quantum well heterostructures

Kiselev

Thorp

et al. 2015

Applied Physics Letters

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“…In this way, subsequent growth of InSb QWs with high mobilities is achieved with remote delta doping (in the range 10-40 m 2 /Vs at 2 K and 4-6 m 2 /Vs at 300 K). 8,9,21,22 Here, we study the electronic properties of two sets of modulation doped InSb/Al x In 1-x Sb QW heterostructures grown by molecular beam epitaxy onto semi-insulating GaAs undoped spacer layer. The two MBL samples differ from each other only in top cap thickness and Te-doping density (fixed spacer thickness) with MBL-2 having a thinner top cap with a nominally higher doping density than MBL-1.…”

Section: Methodsmentioning

confidence: 99%

Suppression of the parasitic buffer layer conductance in InSb/AlxIn1−xSb heterostructures using a wide-band-gap barrier layer

et al. 2011

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InSb/Al x In 1-x Sb heterostructures display intrinsic parallel conduction in the buffer layer at room temperature that limits exploitation of the high-mobility two-dimensional electron gas (2DEG), particularly for nanostructured devices where deep isolation etch processing is impractical. Here, we demonstrate a strategy to reduce the parasitic conduction by the insertion of a pseudomorphic barrier layer of wide-band-gap alloy below the QW. We have studied the high-field magnetotransport in two types of InSb/Al x In 1-x Sb modulation doped quantum well heterostructures with and without the barrier layer in the temperature range 2-290 K and magnetic fields to 7.5 T. The conduction in the doping layer, the 2DEG, and the buffer layer are analyzed using a multi-carrier model that successfully captures the field dependence of the Hall resistance over the experimental field range. Samples with the barrier layer show significantly reduced buffer layer conduction compared to samples without. Our results are expected to be of importance for ambient temperature nano-electronic operation.

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High-mobility electron systems in remotely-doped InSb quantum wells

Cited by 33 publications

References 12 publications

Quantized Conductance and Large g-Factor Anisotropy in InSb Quantum Point Contacts

Quantized Conductance and Large g-Factor Anisotropy in InSb Quantum Point Contacts

Gate-tunable high mobility remote-doped InSb/In1−xAlxSb quantum well heterostructures

Suppression of the parasitic buffer layer conductance in InSb/AlxIn1−xSb heterostructures using a wide-band-gap barrier layer

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