| 51. |
- Mandl, Bernhard, et al.
(författare)
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Self-seeded, position-controlled InAs nanowire growth on Si: A growth parameter study
- 2011
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 334:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the nucleation and growth of InAs nanowires on patterned SiO2/Si(111) substrates is studied. It is found that the nanowire yield is strongly dependent on the size of the etched holes in the SiO2, where openings smaller than 180 nm lead to a substantial decrease in nucleation yield, while openings larger than View the MathML source promote nucleation of crystallites rather than nanowires. We propose that this is a result of indium particle formation prior to nanowire growth, where the size of the indium particles, under constant growth parameters, is strongly influenced by the size of the openings in the SiO2 film. Nanowires overgrowing the etched holes, eventually leading to a merging of neighboring nanowires, shed light into the growth mechanism.
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| 52. |
- Maximov, Ivan, et al.
(författare)
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Nanoimprint lithography for fabrication of three-terminal ballistic junctions in InP/GaInAs
- 2002
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484. ; 13:5, s. 666-668
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Tidskriftsartikel (refereegranskat)abstract
- We present processing technology and characterization results for InP/GaInAs two-dimensional electron gas (2DEG) three-terminal ballistic junction (TBJ) devices manufactured using nanoimprint lithography (NIL). To transfer sub-100 nm features into a high-mobility InP-based 2DEG material, we used SiO2/Si stamps made using electron beam lithography and reactive ion etching. After NIL, the resist residues are removed in oxygen plasma; this is followed by wet etching of InP/GaInAs to define the TBJ structures. Fabricated TBJ devices are characterized using scanning electron microscopy and electron transport measurements. Highly non-linear electrical characteristics as predicted by the theory (Xu H Q 2001 APPI. Phys. Lett. 78 2064) are demonstrated.
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| 53. |
- Maximov, Ivan, et al.
(författare)
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Nanoimprint technology for fabrication of three-terminal ballistic junction devices in GaInAs/InP
- 2003
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Ingår i: Microelectronic Engineering. - 1873-5568. ; 67-8, s. 196-202
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Tidskriftsartikel (refereegranskat)abstract
- We present processing technology based on nanoimprint lithography (NIL) and wet etching for fabrication of GaInAs/InP three-terminal ballistic junction (TBJ) devices. To transfer sub-100 nm features into a high-mobility InP-based 2DEG material, we used SiO2/Si stamps made with electron beam lithography and reactive ion etching. After the NIL, the resist residues are removed in oxygen plasma followed by wet etching of GaInAs/InP to define the M-structures. Fabricated TBJ-devices are characterized using scanning electron microscopy and electron transport measurements. Highly non-linear electrical characteristics of the TBJ structures are demonstrated and compared with E-beam defined devices. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 54. |
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| 55. |
- Mårtensson, Thomas, et al.
(författare)
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Nanowire arrays - a toolbox for the future
- 2004
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Ingår i: Book of extended abstracts: 8th Intl Conf Nanoscale Sci Technol, Venice, Italy (2004).
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Konferensbidrag (refereegranskat)
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| 56. |
- Mårtensson, Thomas, et al.
(författare)
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Nanowire arrays defined by nanoimprint lithography
- 2004
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 4:4, s. 699-702
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the use of nanoimprint lithography to define arrays of vertical InP nanowires. Each nanowire is individually seeded from a catalyzing gold particle and then grown via vapor-liquid-solid growth in a metal-organic vapor phase epitaxy system. The diameter and position of each nanowire can be controlled to create engineered arrays, demonstrated with a hexagonal photonic crystal pattern. This combination of nanoimprint and self-assembly of nanostructures is attractive for photonics and electronics, as well as in life sciences.
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| 57. |
- Nilsson, Henrik, et al.
(författare)
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Correlation-induced conductance suppression at level degeneracy in a quantum dot.
- 2010
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Ingår i: Physical Review Letters. - 1079-7114. ; 104:18
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Tidskriftsartikel (refereegranskat)abstract
- The large, level-dependent g factors in an InSb nanowire quantum dot allow for the occurrence of a variety of level crossings in the dot. While we observe the standard conductance enhancement in the Coulomb blockade region for aligned levels with different spins due to the Kondo effect, a vanishing of the conductance is found at the alignment of levels with equal spins. This conductance suppression appears as a canyon cutting through the web of direct tunneling lines and an enclosed Coulomb blockade region. In the center of the Coulomb blockade region, we observe the predicted correlation-induced resonance. Our findings are supported by numerical and analytical calculations.
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| 58. |
- Nilsson, Henrik, et al.
(författare)
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Giant, level-dependent g factors in InSb nanowire quantum dots.
- 2009
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:9, s. 3151-3156
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Tidskriftsartikel (refereegranskat)abstract
- We report on magnetotransport measurements on InSb nanowire quantum dots. The measurements show that the quantum levels of the InSb quantum dots have giant g factors, with absolute values up to approximately 70, the largest value ever reported for semiconductor quantum dots. We also observe that the values of these g factors are quantum level dependent and can differ strongly between different quantum levels. The presence of giant g factors indicates that considerable contributions from the orbital motion of electrons are preserved in the measured InSb nanowire quantum dots, while the level-to-level fluctuations arise from spin-orbit interaction. We have deduced a value of Delta(SO) = 280 mueV for the strength of spin-orbit interaction from an avoided level crossing between the ground state and first excited state of an InSb nanowire quantum dot with a fixed number of electrons.
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| 59. |
- Nilsson, Henrik, et al.
(författare)
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InSb Nanowire Field-Effect Transistors and Quantum-Dot Devices
- 2011
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 17:4, s. 907-914
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Tidskriftsartikel (refereegranskat)abstract
- The authors present fabrication and electrical measurements of InSb nanowire field-effect transistors (FETs) and quantum dots. The devices are made on a SiO2-capped Si substrate from InSb segments of InAs/InSb heterostructured nanowires, which are grown by metalorganic vapor phase epitaxy. For the FETs, both single- and dual-gate devices are fabricated. The Si substrate is employed as the back gate in both the single-and dual-gate devices, while a top metal gate is employed as a second gate in the dual-gate devices. This top gate is made either as a global gate or as a local finger gate by using a thin HfO2 layer grown by atomic layer deposition as a gate dielectric. The measurements reveal that the fabricated devices show the desired transistor characteristics. The measurements also demonstrate the possibility of realizing ambipolar transistors using InSb nanowires. For InSb nanowire quantum dots, both contact-induced Schottky-barrier-defined devices and top-finger-gate-defined devices are fabricated, and the Si substrate is used as a gate to tune the electron number in the quantum dots. The electrical measurements of these fabricated quantum-dot devices show the Coulomb-blockade effect at 4.2 K. A Fabry-Perot-like interference effect is also observed in a Schottky-barrier-defined quantum device. The authors also discuss in a comparative way, the results of measurements for the InSb nanowire devices made by different fabrication technologies employed in this study.
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| 60. |
- Pettersson, Håkan, 1962-, et al.
(författare)
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Electrical and optical properties of InP nanowire ensemble p(+)-i-n(+) photodetectors
- 2012
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Ingår i: Nanotechnology. - Bristol, UK : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 23:13
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Tidskriftsartikel (refereegranskat)abstract
- We report on a comprehensive study of electrical and optical properties of efficient near-infrared p(+)-i-n(+) photodetectors based on large ensembles of self-assembled, vertically aligned i-n(+) InP nanowires monolithically grown on a common p(+) InP substrate without any buffer layer. The nanowires have a polytype modulated crystal structure of wurtzite and zinc blende. The electrical data display excellent rectifying behavior with an ideality factor of about 2.5 at 300 K. The ideality factor scales with 1/T, which possibly reflects deviations from classical transport models due to the mixed crystal phase of the nanowires. The observed dark leakage current is of the order of merely similar to 100 fA/nanowire at 1 V reverse bias. The detectors display a linear increase of the photocurrent with reverse bias up to about 10 pA/nanowire at 5 V. From spectrally resolved measurements, we conclude that the photocurrent is primarily generated by funneling photogenerated carriers from the substrate into the NWs. Contributions from direct excitation of the NWs become increasingly important at low temperatures. The photocurrent decreases with temperature with an activation energy of about 50 meV, which we discuss in terms of a temperature-dependent diffusion length in the substrate and perturbed transport through the mixed-phase nanowires. © 2012 IOP Publishing Ltd.
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