| 1. |
- Aberg, I, et al.
(författare)
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Nanoscale tungsten aerosol particles embedded in GaAs
- 2002
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Ingår i: Applied Physics Letters. - American Institute of Physics. - 0003-6951. ; 80:16, s. 2976-2978
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Tidskriftsartikel (refereegranskat)abstract
- GaAs containing buried nanoscale tungsten particles has been characterized electrically. The particles were produced using a special aerosol process and were embedded in GaAs by epitaxial overgrowth. Two different particle sizes were investigated separately. When the particle concentration was increased, a conductance drop of about 500 times was observed. A simulation model, based on a random distribution of the particles, was developed and used to support our findings. The major advantage of our method is the simplicity and low processing cost.
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| 2. |
- Balocco, C, et al.
(författare)
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Microwave detection at 110 GHz by nanowires with broken symmetry
- 2005
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Ingår i: NANO LETTERS. - American Chemical Society. - 1530-6984. ; 5:7, s. 1423-1427
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Bao, Jiming, et al.
(författare)
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Nanowire-induced Wurtzite InAs Thin Film on Zinc-Blende InAs Substrate
- 2009
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Ingår i: Advanced Materials. - Wiley-V C H Verlag Gmbh. - 0935-9648. ; 21:36, s. 3654-
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Bao, Jiming, et al.
(författare)
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Optical properties of rotationally twinned InP nanowire heterostructures
- 2008
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Ingår i: Nano Letters. - American Chemical Society. - 1530-6984. ; 8:3, s. 836-841
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Tidskriftsartikel (refereegranskat)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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| 5. |
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| 6. |
- Björk, Mikael, et al.
(författare)
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Few-electron quantum dots in nanowires
- 2004
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Ingår i: Nano Letters. - American Chemical Society. - 1530-6984. ; 4:9, s. 1621-1625
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate transport spectroscopy on bottom-up grown few-electron quantum dots in semiconductor nanowires. The dots are defined by InP double barrier heterostructures in InAs nanowires catalytically grown from nanoparticles. By changing the dot size, we can design devices ranging from single-electron transistors to few-electron quantum dots. In the latter case, electrons can be added one by one to the dots from 0 to similar to50 electrons while maintaining an almost constant charging energy, with addition spectra of the devices displaying shell structures as a result of spin and orbital degeneracies. The reduced dimensionality of the nanowire emitter gives rise to pronounced resonant tunneling peaks, where a gate can be used to control the peak positions.
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| 7. |
- Björk, Mikael, et al.
(författare)
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Heterostructures in one-dimensional nanowires
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science. - Lund Univ.
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Konferensbidrag (refereegranskat)abstract
- Chemical beam epitaxy has been used to grow III/V nanowires seeded from size selected Au aerosol particles. Both chemically uniform InAs wires as well as InAs wires containing one or several heterostructure interfaces were grown. The interfaces were characterized in a transmission electron microscope revealing atomically sharp interfaces and also that, barriers as thin as only 2-3 monolayers and up to several hundred nanometer could be inserted into homogenous InAs wires. Further more, electrical measurements on both homogenous wires and wires containing heterostructures have been performed to investigate the functionality of nanowire based device elements
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| 8. |
- Björk, Mikael, et al.
(författare)
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Nanowire resonant tunneling diodes
- 2002
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Ingår i: APPLIED PHYSICS LETTERS. - AMER INST PHYSICS. - 0003-6951. ; 81:23, s. 4458-4460
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor heterostructures and their implementation into electronic and photonic devices have had tremendous impact on science and technology. In the development of quantum nanoelectronics, one-dimensional (1D) heterostructure devices are receiving a lot of interest. We report here functional 1D resonant tunneling diodes obtained via bottom-up assembly of designed segments of different semiconductor materials in III/V nanowires. The emitter, collector, and the central quantum dot are made from InAs and the barrier material from InP. Ideal resonant tunneling behavior, with peak-to-valley ratios of up to 50:1 and current densities of 1 nA/mum(2) was observed at low temperatures. (C) 2002 American Institute of Physics.
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| 9. |
- Björk, Mikael, et al.
(författare)
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One-dimensional heterostructures in semiconductor nanowhiskers
- 2002
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Ingår i: APPLIED PHYSICS LETTERS. - AMER INST PHYSICS. - 0003-6951. ; 80:6, s. 1058-1060
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Tidskriftsartikel (refereegranskat)abstract
- We report on the growth of designed heterostructures placed within semiconductor nanowhiskers, exemplified by the InAs/InP material system. Based on transmission electron microscopy, we deduce the interfaces between InAs and InP to be atomically sharp. Electrical measurements of thermionic emission across an 80-nm-wide InP heterobarrier, positioned inside InAs whiskers 40 nm in diameter, yield a barrier height of 0.6 eV. On the basis of these results, we propose new branches of physics phenomena as well as new families of device structures that will now be possible to realize and explore.
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| 10. |
- Björk, Mikael, et al.
(författare)
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One-dimensional steeplechase for electrons realized
- 2002
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Ingår i: NANO LETTERS. - AMER CHEMICAL SOC. - 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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