| 1. |
- Balocco, C, et al.
(author)
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Microwave detection at 110 GHz by nanowires with broken symmetry
- 2005
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:7, s. 1423-1427
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Journal article (peer-reviewed)abstract
- By using arrays of nanowires with intentionally broken symmetry, we were able to detect microwaves up to 110 GHz at room temperature. This is, to the best of our knowledge, the highest speed that has been demonstrated in different types of novel electronic nanostructures to date. Our experiments showed a rather stable detection sensitivity over a broad frequency range from 100 MHz to 110 GHz. The novel working principle enabled the nanowires to detect microwaves efficiently without a dc bias. In principle, the need for only one high-resolution lithography step and the planar architecture allow an arbitrary number of nanowires to be made by folding a linear array as many times as required over a large area, for example, a whole wafer. Our experiment on 18 parallel nanowires showed a sensitivity of approximately 75 mV dc output/mW of nominal input power of the 110 GHz signal, even though only about 0.4% of the rf power was effectively applied to the structure because of an impedance mismatch. Because this array of nanowires operates simultaneously, low detection noise was achieved, allowing us to detect -25 dBm 110 GHz microwaves at zero bias with a standard setup.
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| 2. |
- Bao, Jiming, et al.
(author)
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Nanowire-induced Wurtzite InAs Thin Film on Zinc-Blende InAs Substrate
- 2009
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In: Advanced Materials. - : Wiley. - 1521-4095 .- 0935-9648. ; 21:36, s. 3654-3654
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Journal article (peer-reviewed)abstract
- InAs pyramids and platelets on a zinc-blende InAs substrate are found to exhibit a wurtzite crystal structure. induced by wurtzite InAs nanowires, wurtzite InAs thin film and its associated zinc-blende/wurtzite heterocrystalline heterostructures may open up new opportunities in band-gap engineering and related device applications.
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| 3. |
- Bao, Jiming, et al.
(author)
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Optical properties of rotationally twinned InP nanowire heterostructures
- 2008
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:3, s. 836-841
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Journal article (peer-reviewed)abstract
- We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc blende InP nanowires. We have constructed the energy band diagram of the resulting multiquantum well heterostructure and have performed detailed quantum mechanical calculations of the electron and hole wave functions. The excitation power dependent blue-shift of the photoluminescence can be explained in terms of the predicted staggered band alignment of the rotationally twinned zinc blende/wurzite InP heterostructure and of the concomitant diagonal transitions between localized electron and hole states responsible for radiative recombination. The ability of rotational twinning to introduce a heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering.
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| 4. |
- Björk, Mikael, et al.
(author)
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Tunable effective g factor in InAs nanowire quantum dots
- 2005
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 72:20
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Journal article (peer-reviewed)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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| 6. |
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| 7. |
- Bleszynski-Jayich, Ania C., et al.
(author)
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Imaging a one-electron InAs quantum dot in an InAs/InP nanowire
- 2008
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 77:24
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Journal article (peer-reviewed)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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| 8. |
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| 9. |
- Bordag, Michael, et al.
(author)
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Shear stress measurements on InAs nanowires by AFM manipulation
- 2007
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In: Small. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 3:8, s. 1398-1401
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Journal article (peer-reviewed)abstract
- On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.
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| 10. |
- Borg, Mattias, et al.
(author)
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GaAs/GaSb nanowire heterostructures grown by MOVPE
- 2008
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In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 310:18, s. 4115-4121
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Journal article (peer-reviewed)abstract
- We report Au-assisted growth of GaAs/GaSb nanowire heterostructures on GaAs(1 1 1)B-substrates by metal-organic vapor phase epitaxy. The growth is studied at various precursor molar fractions and temperatures, in order to optimize the growth conditions for the GaSb nanowire segment. In contrast to most other III-V nanowire systems, the GaSb nanowire growth is Group V-limited under most conditions. We found that depending on the TMSb molar fraction, the seed particle is either supersaturated AuGa or AuGa2 during GaSb growth. The high Ga content in the particle gives a characteristic diameter increase between the GaAs and GaSb segment. From TEM and XEDS measurements we conclude that the GaSb nanowire growth occurs along either the AuGa-GaSb or AuGa2-GaSb pseudo-binaries of the Au-Ga-Sb ternary phase diagram. Finally, the GaSb nanowires exhibit untapered radial growth on the {1 (1) over bar 0} side facets. (C) 2008 Elsevier B.V. All rights reserved.
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