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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Borgström, Magnus, et al.
(författare)
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Arrays of Ge islands on Si(001) grown by means of electron-beam pre-patterning
- 2003
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484. ; 14:2, s. 264-267
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Tidskriftsartikel (refereegranskat)abstract
- We show that well-defined arrays of self-assembled Ge dots on Si(001) can be grown after pre-patterning the Si surface by means of an electron beam. The electron beam produces C-containing growth masks. The overgrowth of these masks with Si results in pits at the Si surface, in and around which Ge dots nucleate selectively. A manifold of different arrays can be obtained. Almost perfect arrays of quadruples of dots nucleate in the intersections of the four {11n} facets. This way of producing quantum dot arrays is very promising for producing dot structures suitable for use in the study of, for instance, dot-dot tunnelling and related effects.
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| 8. |
- Borgström, Magnus
(författare)
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Epitaxial Growth, Processing and Characterization of Semiconductor Nanostructures
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the growth, processing and characterization of nano-sized structures, eg., self-assembled quantum dots and nano-wires. Such structures are promising candidates for the realization of nano-scale electronic and optical devices, like for instance single electron transistors, resonant tunneling devices, and single photon emitters. For such purposes, the main focus of this work has been on the controlled growth of self-assembled quantum dots. For epitaxy, which is the fundament of this work, low-pressure metal organic vapor phase epitaxy (MOVPE) and ultra high vacuum chemical vapor deposition (UHV-CVD) were used. The structures grown were composed of III/V materials, and SiGe/Si was used for some experiments. For the first group of structures, fundamental investigations on quantum dot growth enabled in-situ growth of InAs/InP self-assembled quantum dot samples in MOVPE. These studies were carried out on freestanding as well as epitaxially overgrown dots. Topography and photo-luminescence were measured with atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FTIR) respectively. InAs/InP low-density quantum dot samples were grown in single or multiple layers, suitable for electrical measurements. These structures were studied by electrical characterization (IV), transmission electron microscopy (TEM), and cross sectional scanning tunneling microscopy (STM). Resonant tunneling through these quantum dots was observed, with peak-to-valley ratios as high as 1300 and negative differential resistance up to a point above the temperature of liquid nitrogen. For the second, more complex, group of structures, patterns on semiconductor surfaces were created, either by electron beam lithography and wet chemical etching, or by the partial overgrowth of electron beam induced carbonaceous material. Spatially ordered growth of III/V and SiGe/Si quantum dots on such patterns was studied by AFM. For the InAs/InP system, conditions were found for which dots could be grown selectively in the patterns by the use of As-P exchange reactions. For the SiGe/Si system, commonly quadruples of islands were observed around each pit. The third group of structures was grown from size selected gold particles, deposited in-house in an aerosol machine, or from Au colloids that were dispersed on the semiconductor surface. These gold particles enabled vapor-liquid-solid (VLS) growth of highly anisotropic one-dimensional structures that were characterized by scanning electron microscopy.
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| 9. |
- Borgström, Magnus, et al.
(författare)
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InAs quantum dots grown on InAlGaAs lattice matched to InP
- 2003
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Ingår i: Journal of Crystal Growth. - 0022-0248. ; 252:4, s. 481-485
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present InAs quantum dots prepared on an InxAlyGa1-x-yAs surface by metal organic vapor phase epitaxy. Atomic force microscopy measurements indicate that dots grown on material with higher Al content are smaller, and that the local dot densities on step-bunched facets formed on the vicinal (0 0 1) surfaces increase. We find that these dots show luminescence at very long wavelengths, lambda(room temperature) approximate to 2.1 mum, and that the emission wavelengths are blue-shifted when the Al content is increased in the layer onto which dot material is deposited. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 10. |
- Borgström, Magnus, et al.
(författare)
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Quadruples of Ge dots grown on patterned Si surfaces
- 2003
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 259:3, s. 262-266
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the results of Ge deposition on a pre-pattemed Si surface. By partially overgrowing nanometer-sized electron beam-induced carbon deposits, faceted pits form at the Si surface and well-defined arrays of self-assembled Ge dots can be grown site selectively in and around those. Typically, four closely spaced Ge islands are formed by preferential nucleation around the pits. By varying the pattern of C-deposits a manifold of different arrays can be obtained. (C) 2003 Elsevier B.V. All rights reserved.
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