| 1. |
- Krishnamachari, U, et al.
(författare)
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Defect-free InP nanowires grown in [001] direction on InP(001)
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:11, s. 2077-2079
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Tidskriftsartikel (refereegranskat)abstract
- We report on [001] InP nanowires grown by metalorganic vapor phase epitaxy directly on (001) InP substrates. Characterization by scanning electron microscopy and transmission electron microscopy reveals wires with nearly square cross sections and a perfect zinc-blende crystalline structure that is free of stacking faults. Photoluminescence measurements of single [001] nanowires exhibit a narrow and intense emission peak at approximately 1.4 eV, whereas <111>B grown reference wires show additional broad luminescence peaks at lower energy. The origin of this uncommon wire growth direction [001] is discussed as a means of controlled formation of [00l]-oriented nanowires on (001) substrates. (C) 2004 American Institute of Physics.
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| 2. |
- Samuelson, Lars, et al.
(författare)
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Semiconductor nanowires for 0D and 1D physics and applications
- 2004
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Ingår i: Physica E: Low-Dimensional Systems and Nanostructures. - : Elsevier BV. - 1386-9477. ; 25:2-3, s. 313-318
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Tidskriftsartikel (refereegranskat)abstract
- During the last 5 years the potential for applications of semiconductor nanowires has grown rapidly via the development of methods for catalytically induced nanowire growth using the, so-called vapor-liquid-solid (VLS) growth mode. The VLS method offers a high degree of control of parameters such as position, diameter, length and composition, including the realization of atomically abrupt heterostructure interfaces inside a nanowire. In this review, we summarize the progress and the standing of our research from the point of view of controlled growth, structural and electronic properties and in terms of different families of devices which have been possible to realize. (C) 2004 Elsevier B.V. All rights reserved.
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| 3. |
- Seifert, Werner, et al.
(författare)
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Growth of one-dimensional nanostructures in MOVPE
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 272:1-4, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- The use of metal organic vapor-phase epitaxy (MOVPE) for growth of one-dimensional nanostructures in the material systems GaAs, GaP, InAs and InP is investigated. Some kinetic effects are discussed, especially the general finding that in MOVPE thinner whiskers grow faster than thicker whiskers. Effects of growth temperature on growth rate and shape of the whiskers, the effects of different growth directions on the perfection of the materials and the possibilities to grow heterostructures in axial and lateral directions are reported. Ways to overcome the randomness in whisker growth by controlled seeding of the Au particles and by using lithography for site control are demonstrated.
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| 4. |
- Borgström, Magnus, et al.
(författare)
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Site control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2003
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Ingår i: Journal of Crystal Growth. - 0022-0248. ; 248, s. 310-316
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Tidskriftsartikel (refereegranskat)abstract
- In this paper. we present the effect of annealing temperature and annealing time on InAs site-controlled quantum dot growth. Individual InAs quantum dots formed by self-assembling have been positioned into holes, created by partial overgrowth of electron beam induced nano-carbon deposits by metal organic vapor phase epitaxy. As/P exchange reactions produce material sufficient for selective dot nucleation in the holes. Results. showing that As/P exchange reactions occur even when capping the dots with InP are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 5. |
- Borgström, Magnus, et al.
(författare)
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Site-control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- We present the effect of annealing temperature and annealing time on InAs/InP site-controlled quantum dot growth. Electron beam pre-patterning forms carbon nano-deposits at the InP surface, which then can be used as growth masks to form nano-holes at the surface. By only annealing of the patterned InP surface under an arsine ambient, As/P exchange reactions produce material sufficient for selective dot nucleation in the holes at the surface
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| 6. |
- Borgström, Magnus, et al.
(författare)
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Site-controlled Ge quantum dot growth on Si by the use of electron beam pre-patterning
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- By growth of Si on substrates that have been pre-patterned by electron-beam induced carbon nano-growth masks, nano-holes form at the Si surface. We have grown self-assembled Ge quantum dots in these holes by ultra high vacuum chemical vapour phase deposition (UHV-CVD). We usually find four dots in each hole. By varying the amount of deposited Ge, we can obtain either four dome-shaped or four pyramid-shaped dots in the majority of holes. These dot arrangements could be used for the realisation of the simplest functional cell for quantum-dot cellular automata (QCA)
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| 7. |
- Borgström, Magnus, et al.
(författare)
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Size- and shape-controlled GaAs nano-whiskers grown by MOVPE: a growth study
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 260:1-2, s. 18-22
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the Au-catalyzed GaAs <111 > B whisker growth under low-pressure metal-organic vapour phase epitaxy conditions. By varying the growth temperature we found a maximum in the whisker growth rate at about 450-475degreesC. With increasing temperature the growth rate decreases due to competing growth at the (111) substrate surface and at the {I 101 whisker side facets, which leads to significant tapering of the whiskers. For low temperatures, the growth rate R in the In R = f (1/T)-plot results in an Arrhenius activation energy of about 67-75 kJ/mol, a value which is in agreement with activation energies reported for low-temperature planar growth of GaAs from TMG and AsH3. The Au acts as a local catalyst and as a collector of reactants, enabling a liquid-phase-epitaxy-like growth with high growth rates at the GaAs (111)B/(Au,Ga) interface.
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| 8. |
- Borgström, Magnus, et al.
(författare)
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Spontaneous InAs quantum dot nucleation at strained InP/GaInAs interfaces
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 83:23, s. 4830-4832
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Tidskriftsartikel (refereegranskat)abstract
- We present a cross-sectional scanning-tunneling microscopy investigation of twofold stacked InAs quantum dots in InP, between layers of GaInAs. The dots are vertically aligned, and images with atomic resolution show that the dots consist of pure InAs. Despite the intended twofold stacking of dots, three dots were often found in the stacks. The third dot formed immediately on top of the final InP layer, at the InP/GaInAs interface. Atomically resolved images of these spontaneously formed dots indicate that they also consist of pure InAs. The effect is discussed in terms of phase segregation of GaInAs and arsenic-phosphorus exchange reactions. (C) 2003 American Institute of Physics.
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| 9. |
- Bryllert, Tomas, et al.
(författare)
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Designed emitter states in resonant tunneling through quantum dots
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:15, s. 2681-2683
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Tidskriftsartikel (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) is compared to tunneling through two layers of vertically aligned (stacked) dots. The difference can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. The temperature dependence of current peaks originating in tunneling through individual QDs and individual stacks is used to clarify this point. In addition, we show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analyzed in a resonant tunneling experiment. (C) 2002 American Institute of Physics.
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| 10. |
- Bryllert, Tomas, et al.
(författare)
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Resonant tunneling through coupled self-assembled quantum dots and the influence of inhomogeneous broadening
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) as well as tunneling through two layers of vertically aligned (stacked) dots is investigated. The difference between single and double layers of QDs can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. By fabricating small-area devices we are able to probe single stacks of quantum dots, revealing details of the coupling between the stacked dots. Very sharp resonances, with peak-to-valley ratios of several hundred, have been measured in the current-voltage characteristics. We also show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analysed in a resonant tunneling experiment
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