| 31. |
- Björk, Mikael, et al.
(författare)
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One-dimensional steeplechase for electrons realized
- 2002
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 2:2, s. 87-89
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Tidskriftsartikel (refereegranskat)abstract
- We report growth of one-dimensional semiconductor nanocrystals, nanowhiskers, in which segments of the whisker with different composition are formed, illustrated by InAs whiskers containing segments of InP. Our conditions for growth allow the formation of abrupt interfaces and heterostructure barriers of thickness from a few monolayers to 100s of nanometers, thus creating a one-dimensional landscape along which the electrons move. The crystalline perfection, the quality of the interfaces, and the variation in the lattice constant are demonstrated by high-resolution transmission electron microscopy, and the conduction band off-set of 0.6 eV is deduced from the current due to thermal excitation of electrons over an InP barrier.
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| 32. |
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| 33. |
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| 34. |
- Björk, Mikael, et al.
(författare)
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Tunable effective g factor in InAs nanowire quantum dots
- 2005
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 72:20
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Tidskriftsartikel (refereegranskat)abstract
- 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 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 vertical bar g(*)vertical bar=13 down to vertical bar g(*)vertical bar=2.3 for the smallest dots.
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| 35. |
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| 36. |
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| 37. |
- Bleszynski-Jayich, Ania C., et al.
(författare)
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Imaging a one-electron InAs quantum dot in an InAs/InP nanowire
- 2008
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 77:24
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Tidskriftsartikel (refereegranskat)abstract
- Nanowire heterostructures define high-quality few-electron quantum dots for nanoelectronics, spintronics, and quantum information processing. We use a cooled scanning probe microscope (SPM) to image and control an InAs quantum dot in an InAs/InP nanowire using the tip as a movable gate. Images of dot conductance vs tip position at T=4.2 K show concentric rings as electrons are added, starting with the first electron. The SPM can locate a dot along a nanowire and individually tune its charge, abilities that will be very useful for the control of coupled nanowire dots.
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| 38. |
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| 39. |
- Bolinsson, Jessica, et al.
(författare)
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Diffusion length measurements in axial and radial heterostructured nanowires using cathodoluminescence
- 2011
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 315:1, s. 138-142
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Konferensbidrag (refereegranskat)abstract
- We have measured the ambipolar diffusion lengths in nanowires with GaAs and AlGaAs core material using cathodoluminescence imaging. This was done by combining III-V semiconductor materials with different bandgaps in single nanowires. We show that it is possible to record intensity profiles of the emission from segments of lower bandgap material positioned along the nanowire length and in this way gain an insight on important carrier transport properties of the nanowire core material. We present diffusion data for GaAs and AlGaAs nanowire core material in different radially and axially heterostructured nanowires and show that the diffusion of carriers is greatly increased by capping the nanowires with a higher-bandgap material. In addition, we show how a decoupling of the radial and axial growth during particle-seeded growth is necessary in order to reach long diffusion lengths along the core of axially heterostructured nanowires. In addition, for ternary compounds (InGaAs and AlGaAs), we observe compositional differences for radial and axial nanowire growth. (C) 2010 Elsevier B.V. All rights reserved.
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| 40. |
- Bolinsson, Jessica, et al.
(författare)
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GaAs/AlGaAs heterostructure nanowires studied by cathodoluminescence
- 2014
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Ingår i: Nano Reseach. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 7:4, s. 473-490
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Tidskriftsartikel (refereegranskat)abstract
- In this report we explore the structural and optical properties of GaAs/AlGaAs heterostructure nanowires grown by metalorganic vapour phase epitaxy using gold seed-particles. The optical studies were done by low-temperature cathodoluminescence (CL) in a scanning electron microscope (SEM). We perform a systematic investigation of how the nanowire growth-temperature affects the total photon emission, and variations in the emission energy and intensity along the length of the nanowires. The morphology and crystal structures of the nanowires were investigated using SEM and transmission electron microscopy (TEM). In order to correlate specific photon emission characteristics with variations in the nanowire crystal structure directly, TEM and spatially resolved CL measurements were performed on the same individual nanowires. We found that the main emission energy was located at around 1.48 eV, and that the emission intensity was greatly enhanced when increasing the GaAs nanowire core growth temperature. The data strongly suggests that this emission energy is related to rotational twins in the GaAs nanowire core. Our measurements also show that radial overgrowth by GaAs on the GaAs nanowire core can have a deteriorating effect on the optical quality of the nanowires. Finally, we conclude that an in situ pre-growth annealing step at a sufficiently high temperature significantly improves the optical quality of the nanowires.
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