One-dimensional heterostructures in semiconductor nanowhiskers

Björk, Mikael; Ohlsson, Björn; Sass, T; Persson, Ann; Thelander, Claes; Magnusson, Martin H.; Deppert, Knut; Wallenberg, L. Reine; Samuelson, Lars

doi:10.1063/1.1447312

Cited by 603 publications

(484 citation statements)

References 17 publications

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“…As a result, nanoribbons have a rectangular cross section. TEM studies on a wide nanoribbon ( Figure 2B) reveal similar crystalline characteristics to the narrow nanoribbon ( Figure 2A); it grows along [11][12][13][14][15][16][17][18][19][20] direction as well. The TEM data of a nanowire with rough surface are shown in Figure 2C.…”

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confidence: 77%

“…The corresponding selected-area electron diffraction (SAED) pattern (inset of Figure 2A) exhibits a clear hexagonally symmetric spots pattern, confirming the single crystalline nature. A high resolution TEM (HRTEM) image (inset in Figure 2A) shows hexagonal lattice fringes with a correct lattice spacing of 2.1 Å between (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) planes. SAED patterns and HRTEM images demonstrate that the nanoribbons grow along [11][12][13][14][15][16][17][18][19][20] direction, with (0001) facets as top and bottom surfaces and (1-100) facets as side surfaces.…”

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confidence: 99%

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Topological Insulator Nanowires and Nanoribbons

Kong¹,

Randel

Peng³

et al. 2009

Nano Lett.

315

334

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Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi 2 Se 3 material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi 2 Se 3 nanomaterials with a variety of morphologies. The synthesis of Bi 2 Se 3 nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [11][12][13][14][15][16][17][18][19][20] direction with a rectangular crosssection and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitals to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states.Bi 2 Se 3 is a narrow gap semiconductor, previously studied for infrared detectors and thermoelectric applications. 1 Recently, research on Bi2Se3 and related compounds (Bi2Te3 and Sb2Te3) has attracted much interest because they are predicted to be three-dimensional (3D) topological insulators (TIs), a new class of quantum matter possessing conducting surface states with nondegenerate spins. 2 In TIs, the strong spin-orbit coupling dictates robust, nontrivial surface states, which are topologically protected against back scattering from time-reversal invariant defects and impurities. Angleresolved photoemission spectroscopy (ARPES) measurements on bulk single crystals of BixSb1-x, Bi2Se3, and Bi2Te3 have verified the existence of the 3D TI phase. [3][4][5][6][7] In particular, the surface states of Bi2Se3 forms a single Dirac cone inside a large bulk band gap of 0.3 eV, thus being suggested as the reference material for the 3D TIs. 2,4,8 The unique properties of the Bi2Se3 TI may pave the way for dissipationless quantum electronics and room temperature spintronics applications.1 To date, the surface properties of the 3D TIs have been mainly investigated by ARPES measurements on the cleaved surface of bulk crystals. [3][4][5][6][7] Single crystalline nanostructure, on the other hand, offers an attractive alternative system to study the surface sta...

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mentioning

confidence: 77%

mentioning

confidence: 99%

Topological Insulator Nanowires and Nanoribbons

Kong¹,

Randel

Peng³

et al. 2009

Nano Lett.

315

334

View full text Add to dashboard Cite

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“…Due to their small diameters, large surface-tovolume ratios, and novel electronic and optical properties, nanowires are objects of intense study in fundamental science. [1][2][3][4][5] One of the consequences related to the large surface-to-volume ratio is the crystallization of nanowires in crystalline structures that are not stable in the bulk form. [6][7][8][9][10][11] In the case of nanowires pertaining to the arsenides and phosphides, it is very common to find rotational twins along with polytypism between wurtzite and zinc-blende structures.…”

Section: Introductionmentioning

confidence: 99%

Raman spectroscopy of wurtzite and zinc-blende GaAs nanowires: Polarization dependence, selection rules, and strain effects

et al. 2009

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Polarization-dependent Raman scattering experiments realized on single GaAs nanowires with different percentages of zinc-blende and wurtzite structure are presented. The selection rules for the special case of nanowires are found and discussed. In the case of zinc-blende, the transversal optical mode E 1 ͑TO͒ at 267 cm −1 exhibits the highest intensity when the incident and analyzed polarization are parallel to the nanowire axis. This is a consequence of the nanowire geometry and dielectric mismatch with the environment, and in quite good agreement with the Raman selection rules. We also find a consistent splitting of 1 cm −1 of the E 1 ͑TO͒. The transversal optical mode related to the wurtzite structure, E 2 H , is measured between 254 and 256 cm −1 , depending on the wurtzite content. The azimuthal dependence of E 2 H indicates that the mode is excited with the highest efficiency when the incident and analyzed polarization are perpendicular to the nanowire axis, in agreement with the selection rules. The presence of strain between wurtzite and zinc-blende is analyzed by the relative shift of the E 1 ͑TO͒ and E 2 H modes. Finally, the influence of the surface roughness in the intensity of the longitudinal optical mode on ͕110͖ facets is presented.

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“…We show that varying the size of our nanowire dots allows us to tune g * from a value close to the InAs bulk value down to |g * | = 2.3±0.3. The possibility to have multiple dots along a nanowire, each with a different g-factor, makes such systems interesting candidates for realizations of individually addressable spin qubits.Using chemical beam epitaxy InAs nanowires containing QDs were grown catalytically from Au nanoparticles deposited on a <111>B InAs substrate [11,12]. The * Electronic address: andreas.fuhrer@ftf.lth.se nanowires typically grow perpendicular to the substrate and high resolution scanning transmission electron microscope (STEM) images indicate that most of them…”

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confidence: 99%

“…Using chemical beam epitaxy InAs nanowires containing QDs were grown catalytically from Au nanoparticles deposited on a <111>B InAs substrate [11,12]. The * Electronic address: andreas.fuhrer@ftf.lth.se nanowires typically grow perpendicular to the substrate and high resolution scanning transmission electron microscope (STEM) images indicate that most of them…”

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confidence: 99%

Tunable effectivegfactor in InAs nanowire quantum dots

et al. 2005

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We report tunneling spectroscopy measurements of the Zeeman spin splitting in InAs few-electron quantum dots. The dots are formed between two InP barriers in InAs nanowires with a wurtzite crystal structure which are grown using chemical beam epitaxy. The values of the electron g-factors of the first few electrons entering the dot are found to strongly depend on dot size. They range from close to the InAs bulk value in large dots |g * | = 13 down to |g * | = 2.3 for the smallest dots.PACS numbers: 73.23. Hk, 73.63.Kv, 71.70.Ej The spin of an electron in a quantum dot (QD) is one of the candidates for a scaleable quantum bit, the fundamental unit in quantum computation and quantum communication schemes [1]. Experimental realizations are on the one hand pursued using top-down approaches. This usually involves lateral gate electrodes electrostatically confining few or a single electron in a two dimensional electron gas close to the surface of a Ga(Al)As based heterostructure [2]. Such systems offer good tunability and controlled coupling of multiple spins has been demonstrated [3]. On the other hand, bottom up systems such as self assembled QDs [4] and carbon nanotubes [5] are expected to scale more easily. Semiconductor nanowires have emerged as a promising bottom-up fabricated system for electronic and optical device applications [6]. We have recently demonstrated the creation of few-electron QDs using InAs nanowire heterostructures [7] with two InP barriers. In the following we set out to investigate the spin properties of the first few orbital levels of these QDs.We utilize transport spectroscopy to measure the Zeeman splitting of the energy levels as a function of magnetic field and thereby determine the effective electron g-factor (g * ). The g-factor of bulk InAs, which crystalizes in the zinc-blende (ZB) structure, has been found to be g * = −14.7 [8]. However, InAs nanowires can exhibit both zinc-blende and wurtzite (WZ) type crystal structure[9] depending on diameter and growth conditions and so far very little is known about band parameters in WZ InAs. In low-dimensional semiconductor heterostructures the g factor depends critically on system size and dimensionality [10]. We show that varying the size of our nanowire dots allows us to tune g * from a value close to the InAs bulk value down to |g * | = 2.3±0.3. The possibility to have multiple dots along a nanowire, each with a different g-factor, makes such systems interesting candidates for realizations of individually addressable spin qubits.Using chemical beam epitaxy InAs nanowires containing QDs were grown catalytically from Au nanoparticles deposited on a <111>B InAs substrate [11,12]. The * Electronic address: andreas.fuhrer@ftf.lth.se nanowires typically grow perpendicular to the substrate and high resolution scanning transmission electron microscope (STEM) images indicate that most of them

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One-dimensional heterostructures in semiconductor nanowhiskers

Cited by 603 publications

References 17 publications

Topological Insulator Nanowires and Nanoribbons

Topological Insulator Nanowires and Nanoribbons

Raman spectroscopy of wurtzite and zinc-blende GaAs nanowires: Polarization dependence, selection rules, and strain effects

Tunable effectivegfactor in InAs nanowire quantum dots

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