| 1. |
- Anttu, Nicklas, et al.
(författare)
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Drastically increased absorption in vertical semiconductor nanowire arrays: A non-absorbing dielectric shell makes the difference
- 2012
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Ingår i: Nano Reseach. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 5:12, s. 863-874
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Tidskriftsartikel (refereegranskat)abstract
- Enhanced absorption of especially long wavelength light is needed to enable the full potential of semiconductor nanowire (NW) arrays for optoelectronic applications. We show both experimentally and theoretically that a transparent dielectric shell (Al2O3 coating) can drastically improve the absorption of light in InAs NW arrays. With an appropriate thickness of the Al2O3 shell, we achieve four times stronger absorption in the NWs compared to uncoated NWs and twice as good absorption as when the dielectric completely fills the space between the NWs. We provide detailed theoretical analysis from a combination of full electrodynamic modeling and intuitive electrostatic approximations. This reveals how the incident light penetrates better into the absorbing NW core with increasing thickness of the dielectric shell until a resonant shell thickness is reached. We provide a simple description of how to reach this strongly absorbing resonance condition, making our results easy to apply for a broad wavelength range and a multifold of semiconductor and dielectric coating material combinations.
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| 2. |
- Anttu, Nicklas, et al.
(författare)
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Excitations of surface plasmon polaritons in double layer metal grating structures
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:9
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Tidskriftsartikel (refereegranskat)abstract
- We study the light scattering properties of double layer gratings (DLGs) made from Au on SiO2 substrates. It is found that surface plasmon polaritons (SPPs) can be excited in the DLGs for a separation of up to 150 nm between the two Au grating layers and the collective reflectance spectra exhibit a strong resonant peak and a closely lying dip as a result of the surface plasmon polariton excitations. It is also found that the angle-resolved specular reflectance spectra show a dip-peak pair structure, while the angle-resolved reflectance spectra of higher diffracted orders show a complementary peak-dip pair structure. Finally, operation of the DLGs for efficient wavelength demultiplexing is proposed and discussed in light of these results. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3690947]
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| 3. |
- Chen, Jianing, et al.
(författare)
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Probing Strain in Bent Semiconductor Nanowires with Raman Spectroscopy.
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:4, s. 1280-1286
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Tidskriftsartikel (refereegranskat)abstract
- We present a noninvasive optical method to determine the local strain in individual semiconductor nanowires. InP nanowires were intentionally bent with an atomic force microscope and variations in the optical phonon frequency along the wires were mapped using Raman spectroscopy. Sections of the nanowires with a high curvature showed significantly broadened phonon lines. These observations together with deformation potential theory show that compressive and tensile strain inside the nanowires is the physical origin of the observed phonon energy variations.
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| 4. |
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| 5. |
- Chen, Jianing, et al.
(författare)
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Surface-enhanced Raman scattering of rhodamine 6G on nanowire arrays decorated with gold nanoparticles
- 2008
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19:27, s. 5-275712
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the surface-enhanced Raman scattering (SERS) of rhodamine 6G (R6G) adsorbed on Au nanoparticles attached to InP nanowires. We find that nanowire arrays act as frameworks for effective SERS substrates with a significantly higher Raman signal sensitivity than a planar framework of Au nanoparticles adsorbed two-dimensionally on a flat surface. The SERS signal displays a clear polarization-dependent effect when the nanowires are arranged in a row. We also find that the SERS signal increases with time during continuous laser illumination. The plasmon-enhanced optical forces between Au nanoparticles may either move pairs of nanoparticles closer together or attract adsorbed molecules by moving them to the junctions of Au nanoparticle aggregates. Such effects by plasmon optical forces may cause the observed increase of the SERS signal with continuous laser illumination.
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| 6. |
- Chen, Jianing, et al.
(författare)
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Tip-enhanced Raman scattering of p-thiocresol molecules on individual gold nanoparticles
- 2008
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 92:9
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of tip-enhanced Raman scattering on Au aerosol nanoparticles deposited on gold films. Under the tunneling current state, the Au tip and the Au aerosol nanoparticle form a narrow cavity, where large electromagnetic field enhancements are created to enhance Raman scattering enormously. Colorless p-thiocresol molecules are used as probe molecules. The estimated Raman enhancement is about nine orders of magnitude for the tip/particle configuration.
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| 7. |
- Ma, Liang, et al.
(författare)
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Room-Temperature Near-Infrared Photodetectors Based on Single Heterojunction Nanowires
- 2014
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 14:2, s. 694-698
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Tidskriftsartikel (refereegranskat)abstract
- Nanoscale near-infrared photodetectors are attractive for their potential applications in integrated optoelectronic devices. Here we report the synthesis of GaSb/GaInSb p-n heterojunction semiconductor nanowires for the first time through a controllable chemical vapor deposition (CVD) route. Based on these nanowires, room-temperature, high-performance, near-infrared photodetectors were constructed. The fabricated devices show excellent light response in the infrared optical communication region (1.55 mu m), with an external quantum efficiency of 10(4), a responsivity of 10(3) A/W, and a short response time of 2 ms, which shows promising potential applications in integrated photonics and optoelectronics devices or systems.
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| 8. |
- Xu, Guangwei, et al.
(författare)
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Synthesis, properties, and top-gated metal-oxide-semiconductor field-effect transistors of p-type GaSb nanowires
- 2013
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 3:43, s. 19834-19839
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Tidskriftsartikel (refereegranskat)abstract
- High-quality GaSb nanowires (NWs) have been synthesized via chemical vapor deposition. The as-synthesized NWs have a zinc-blende structure with growth direction along a < 011 > direction. Raman spectrum of the GaSb NWs consists of two peaks, corresponding to the LO and TO phonon modes, respectively. The temperature dependence of the photoluminescence spectra shows a blue-shift as the temperature decreases from 300 to 13 K. The electrical properties of the GaSb NWs are investigated over a wide range of temperatures from 25 mK to 291 K. The results show that the GaSb NWs exhibit excellent p-type transistor performance at low temperatures (<40 K). The room-temperature hole density and mobility were found to be similar to 2.2 x 10(18) cm(-3) and similar to 14.2 cm(2) V-1 s(-1), respectively. The Schottky contact characteristics were observed and the barrier height was found to be similar to 14 meV. Our results show that the GaSb NWs could be used as building blocks for emerging p-type nanoelectronic devices in extremely low temperature environments.
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| 9. |
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| 10. |
- Xu, Hongxing, et al.
(författare)
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Unified treatment of fluorescence and Raman scattering processes near metal surfaces
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 93:24
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Tidskriftsartikel (refereegranskat)abstract
- We present a general model study of surface-enhanced resonant Raman scattering and fluorescence focusing on the interplay between electromagnetic effects and the molecular dynamics. Our model molecule is placed close to two Ag nanoparticles and has two electronic levels. A Franck-Condon mechanism provides electron-vibration coupling. Using realistic parameter values for the molecule we find that an electromagnetic enhancement by 10 orders of magnitude can yield Raman cross sections sigma(R) of the order 10(-14) cm(2). We also discuss the dependence of sigma(R) on incident laser intensity.
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| 11. |
- ZhiQiang, Guan, et al.
(författare)
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Surface-enhanced Raman scattering on dual-layer metallic grating structures
- 2010
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Ingår i: Chinese Science Bulletin. - : Springer Science and Business Media LLC. - 1001-6538 .- 1861-9541. ; 55:24, s. 2643-2648
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Tidskriftsartikel (refereegranskat)abstract
- Dual-layer Metallic grating (DMG) structures as surface-enhanced Raman scattering (SERS) substrates are studied using benzenethiol as the probe analyte. The DMG structure consists of a SiO2 grating and 100-nm-thick gold coating layers. An enhancement factor of 10(5) is achieved by optimizing the SiO2 grating height within the range from 165 to 550 nm. The enhancement factor dependence on the SiO2 grating height is due to the surface plasmon excitation, which is dependent on the polarization of the incident light, and confirmed by finite difference time domain simulations. This study demonstrates the advantages of high uniformity, reproducibility and sensitivity in the DMG structures for SERS applications.
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| 12. |
- Abay, Simon, 1980, et al.
(författare)
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Charge transport in InAs nanowire Josephson junctions
- 2014
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969 .- 1098-0121. ; 89:21, s. 214508-
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Tidskriftsartikel (refereegranskat)abstract
- We present an extensive experimental and theoretical study of the proximity effect in InAs nanowires connected to superconducting electrodes. We fabricate and investigate devices with suspended gate-controlled nanowires and nonsuspended nanowires, with a broad range of lengths and normal-state resistances. We analyze the main features of the current-voltage characteristics: the Josephson current, excess current, and subgap current as functions of length, temperature, magnetic field, and gate voltage, and compare them with theory. The Josephson critical current for a short-length device, L = 30 nm, exhibits a record high magnitude of 800 nA at low temperature that comes close to the theoretically expected value. The critical current in all other devices is typically reduced compared to the theoretical values. The excess current is consistent with the normal resistance data and agrees well with the theory. The subgap current shows a large number of structures; some of them are identified as subharmonic gap structures generated by multiple Andreev reflection. The other structures, detected in both suspended and nonsuspended devices, have the form of voltage steps at voltages that are independent of either the superconducting gap or length of the wire. By varying the gate voltage in suspended devices, we are able to observe a crossover from typical tunneling transport at large negative gate voltage, with suppressed subgap current and negative excess current, to pronounced proximity junction behavior at large positive gate voltage, with enhanced Josephson current and subgap conductance as well as a large positive excess current.
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| 13. |
- Abay, Simon, 1980, et al.
(författare)
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High Critical-Current Superconductor-InAs Nanowire-Superconductor Junctions
- 2012
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 12:11, s. 5622-5625
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Tidskriftsartikel (refereegranskat)abstract
- We report on the fabrication of InAs nanowires coupled to superconducting leads with high critical current and widely tunable conductance. We implemented a double lift off nanofabrication Method to get very short nanowire devices with Ohmic contacts. We observe very high critical. currents of up to 800 nA in a wire with a diameter of 80 nm. The current- voltage characteristics of longer and suspended nanowires display,either. Coulomb blockade or supercurrent depending on a local gate voltage, combining different regimes of transport in a single device.
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| 14. |
- Abay, Simon, 1980, et al.
(författare)
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Quantized Conductance and Its Correlation to the Supercurrent in a Nanowire Connected to Superconductors
- 2013
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:8, s. 3614-3617
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Tidskriftsartikel (refereegranskat)abstract
- We report conductance and supercurrent of InAs nano wires coupled to Al-superconducting electrodes with short channel lengths and good Ohmic contacts. The nanowires are suspended 15 nm above a local gate electrode. The charge density in the nanowires can be controlled by a small change in the gate voltage. For large negative gate voltages, the number of conducting channels is reduced gradually, and we observe a stepwise decrease of both conductance and critical current before the conductance vanishes completely.
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| 15. |
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| 16. |
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| 17. |
- Anttu, Nicklas, et al.
(författare)
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Coupling of Light into Nanowire Arrays and Subsequent Absorption
- 2010
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Ingår i: Journal of Nanoscience And Nanotechnology. - : American Scientific Publishers. - 1533-4899 .- 1533-4880. ; 10:11, s. 7183-7187
-
Konferensbidrag (refereegranskat)abstract
- We present a theoretical study of the absorption of light in periodic arrays of InP nanowires. The absorption in the array depends strongly on the diameter and the length of the nanowires, as well as the period of the array. Nanowires of a length of just 2 Am are able, after an appropriate choice for the other parameters, to absorb more than 90% of the incident energy of TE and TM polarized light, with photon energies almost all the way down to the band gap energy and an incidence angle up to 50 degree. This high total absorption arises from a good coupling of the incident light into the nanowire array at the top interface between air and the array and absorption inside the array before the light reaches the interface between the nanowires and the substrate. We find that for a given photon energy there exists a critical nanowire diameter above which a dramatic increase in the absorption occurs. The critical diameter decreases for increasing photon energies, and is directly related to the dispersion of waveguiding modes in single isolated nanowires. A characterization showed that the absorption characteristics of the nanowire arrays are very promising for photovoltaic applications.
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| 18. |
- Anttu, Nicklas, et al.
(författare)
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Efficient light management in vertical nanowire arrays for photovoltaics
- 2013
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Ingår i: Optics Express. - 1094-4087. ; 21:9, s. 558-575
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Tidskriftsartikel (refereegranskat)abstract
- Vertical arrays of direct band gap III-V semiconductor nanowires (NWs) hold the prospect of cheap and efficient next-generation photovoltaics, and guidelines for successful light-management are needed. Here, we use InP NWs as a model system and find, through electrodynamic modeling, general design principles for efficient absorption of sun light in nanowire arrays by systematically varying the nanowire diameter, the nanowire length, and the array period. Most importantly, we discover the existence of specific band-gap dependent diameters, 170 nm and 410 nm for InP, for which the absorption of sun light in the array is optimal, irrespective of the nanowire length. At these diameters, the individual InP NWs of the array absorb light strongly for photon energies just above the band gap energy due to a diameter-tunable nanophotonic resonance, which shows up also for other semiconductor materials of the NWs. Furthermore, we find that for maximized absorption of sun light, the optimal period of the array increases with nanowire length, since this decreases the insertion reflection losses. (C) 2013 Optical Society of America
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| 19. |
- Anttu, Nicklas, et al.
(författare)
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Light scattering and plasmon resonances in a metal film with sub-wavelength nano-holes
- 2008
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 100, s. 052037-052037
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Konferensbidrag (refereegranskat)abstract
- We report on a theoretical study of optical extinction in a metal film of 15-230 nm in thickness patterned periodically with sub-wavelength nano-holes of 140 nm in diameter. The gold plate was on a thick SiO2 wafer and the nano-holes as well as the top side of the metal plate were filled with water or solvent. Light was sent in toward the plate from the SiO2 side. The simulations were performed by solving the Maxwell equations using the scattering matrix method. It was seen that the extinction can, depending on the periodicity of the hole array, show one or several peaks in the visible wavelength range. The positions of the peaks were redshifted when the thickness of the gold plate was decreased. It was found that the peak positions for a thick plate can be identified from a simple surface plasmon dispersion relation.
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| 20. |
- Anttu, Nicklas, et al.
(författare)
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Optical Far-Field Method with Subwavelength Accuracy for the Determination of Nanostructure Dimensions in Large-Area Samples.
- 2013
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:6, s. 2662-2667
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Tidskriftsartikel (refereegranskat)abstract
- The physical, chemical, and biological properties of nanostructures depend strongly on their geometrical dimensions. Here we present a fast, noninvasive, simple-to-perform, purely optical method that is capable of characterizing nanostructure dimensions over large areas with an accuracy comparable to that of scanning electron microscopy. This far-field method is based on the analysis of unique fingerprints in experimentally measured reflectance spectra using full three-dimensional optical modeling. We demonstrate the strength of our method on large-area (millimeter-sized) arrays of vertical InP nanowires, for which we simultaneously determine the diameter and length as well as cross-sample morphological variations thereof. Explicitly, the diameter is determined with an accuracy better than 10 nm and the length with an accuracy better than 30 nm. The method is versatile and robust, and we believe that it will provide a powerful and standardized measurement technique for large-area nanostructure arrays suitable for both research and industrial applications.
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| 21. |
- Anttu, Nicklas, et al.
(författare)
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Scattering matrix method for optical excitation of surface plasmons in metal films with periodic arrays of subwavelength holes
- 2011
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 83:16
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Tidskriftsartikel (refereegranskat)abstract
- We present the formulation of a scattering matrix method for the study of light-scattering properties of metal films. The method is employed for the study of the optical excitation of surface plasmons in a gold film of 15-230 nm thickness, patterned periodically with subwavelength nanoholes. The gold film is placed on a thick SiO2 wafer, and the nanoholes as well as the top side of the gold film are filled with H2O. Light is incident on the gold film from either the SiO2 or the H2O side. The extinction and reflectance spectra of the system, as well as the electromagnetic field distributions at certain characteristic wavelengths, are calculated. The extinction spectra show, depending on system parameters, one or several peaks in the visible wavelength range. The extinction peaks are found to be caused by surface plasmons. A simple model based on the dispersion relation for surface plasmons in an unperforated gold film is shown to predict the peak positions of the extinction for thick perforated films very well. Even for thin films, this simple model, which includes coupling of surface plasmons on both surfaces of the film, predicts peak positions of the extinction well if the hole diameter is small enough. As the hole diameter increases, the extinction peaks of thin films show redshifts. Extinction peaks caused by surface plasmons at the SiO2/Au interface in thick films exhibit strong redshifts when the film thickness is decreased. However, the extinction peaks caused by surface plasmons at the H2O/Au interface in thick films show a completely different behavior. In this case, the extinction peaks do not move noticeably when the film thickness is decreased. Instead, they are weakened and finally disappear. It is also found that each extinction peak is accompanied by an extinction dip and that a reflectance dip is located in the wavelength between the extinction peak and the dip. This arrangement of an extinction peak, a reflectance dip, and an extinction dip is a general property of the surface-plasmon excitation. The calculated electromagnetic field distributions in both thick and thin films show clearly the signature of the excitation of surface plasmons at the extinction peaks, the extinction dips, and the reflectance dips. In thick films with small holes, the electric-field strength in the vicinity of the holes is weak at wavelengths for which surface plasmons are excited. In contrast to this, for thin films at the surface-plasmon excitations, a much stronger electric field is seen in the vicinity of the holes.
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| 22. |
- 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 (ACS). - 1530-6992 .- 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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| 23. |
- Beyer, Jan, 1980-
(författare)
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Spin Properties in InAs/GaAs Quantum Dot based Nanostructures
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Semiconductor quantum dots (QDs) are a promising building block of future spin-functional devices for applications in spintronics and quantum information processing. Essential to the realization of such devices is our ability to create a desired spin orientation of charge carriers (electrons and holes), typically via injection of spin polarized carriers from other parts of the QD structures. In this thesis, the optical orientation technique has been used to characterize spin generation, relaxation and detection in self-assembled single and multi-QD structures in the InAs/GaAs system prepared by modern molecular beam epitaxy technique.Optical generation of spin-oriented carriers in the wetting layer (WL) and GaAs barrier was carried out via circularly polarized excitation of uncorrelated electron-hole pairs from band-to-band transitions or via resonant excitation of correlated electron-hole pairs, i.e. excitons. It was shown that the generation and injection of uncorrelated electron-hole pairs is advantageous for spin-preserving injection into the QDs. The lower spin injection efficiency of excitons was attributed to an enhanced spin relaxation caused by the mutual electron-hole Coulomb exchange interaction. This correlation affects the spin injection efficiency up to elevated temperatures of around 150 K.Optical orientation at the energy of the WL light-hole (lh) exciton (XL) is accompanied by simultaneous excitation from the heavy-hole (hh) valence band at high ~k-vectors. Quantum interference of the two excitation pathways in the spectral vicinity of the XL energy resulted in occurrence of an asymmetric absorption peak, a Fano resonance. Complete quenching of spin generation efficiency at the resonance was observed and attributed to enhanced spin scattering between the hh and lh valence bands in conjunction with the Coulomb exchange interaction in the XL. This mechanism remains effective up to temperatures exceeding 100 K.In longitudinal magnetic fields up to 2 T, the spin detection efficiency in the QD ensemble was observed to increase by a factor of up to 2.5 in the investigated structures. This is due to the suppression of two spin depolarization mechanisms of the QD electron: the hyperfine interaction with the randomly oriented nuclear spins and the anisotropic exchange interaction with the hole. At higher magnetic fields, when these spin depolarization processes are quenched, only anisotropic QD structures (such as double QDs, aligned along a specific crystallographic axis) still exhibit a rather strong field dependence of the QD electron spin polarization under non-resonant excitation. Here, an increased spin relaxation in the spin injector, i.e. the WL or GaAs barrier, is suggested to lead to more efficient thermalization of the spins to the lower Zeeman-split spin state before capture to the QD.Finally, the influence of elevated temperatures on the spin properties of the QD structures was studied. The temperature dependence of dynamic nuclear polarization (DNP) of the host lattice atoms in the QDs and its effect on the QD electron spin relaxation and dephasing were investigated for temperatures up to 85 K. An increase in DNP efficiency with temperature was found, accompanied by a decrease in the extent of spin dephasing. Both effects are attributed to an accelerating electron spin relaxation, suggested to be due to phonon-assisted electronnuclear spin flip-flops driven by the hyperfine interaction. At even higher temperatures, reaching up to room temperature, a surprising, sharp rise in the QD polarization degree has been found. Experiments in a transverse magnetic field showed a rather constant QD spin lifetime, which could be governed by the spin dephasing time T*2. The observed rising in QD spin polarization degree could be likely attributed to a combined effect of shortening of trion lifetime and increasing spin injection efficiency from the WL. The latter may be caused by thermal activation of non-radiative carrier relaxation channels.
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| 24. |
- Boxberg, Fredrik, et al.
(författare)
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Elastic and Piezoelectric Properties of Zincblende and Wurtzite Crystalline Nanowire Heterostructures.
- 2012
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Ingår i: Advanced Materials. - : Wiley. - 1521-4095 .- 0935-9648. ; 24:34, s. 4692-4706
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Tidskriftsartikel (refereegranskat)abstract
- The elastic and piezoelectric properties of zincblende and wurtzite crystalline InAs/InP nanowire heterostructures have been studied using electro-elastically coupled continuum elasticity theory. A comprehensive comparison of strains, piezoelectric potentials and piezoelectric fields in the two crystal types of nanowire heterostructures is presented. For each crystal type, three different forms of heterostructures-core-shell, axial superlattice, and quantum dot nanowire heterostructures-are considered. In the studied nanowire heterostructures, the principal strains are found to be insensitive to the change in the crystal structure. However, the shear strains in the zincblende and wurtzite nanowire heterostructures can be very different. All the studied nanowire heterostructures are found to exhibit a piezoelectric field along the nanowire axis. The piezoelectric field is in general much stronger in a wurtzite nanowire heterostructure than in its corresponding zincblende heterostructure. Our results are expected to be particularly important for analyzing and understanding the properties of epitaxially grown nanowire heterostructures and for applications in nanowire electronics, optoelectronics, and biochemical sensing.
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| 25. |
- Boxberg, Fredrik, et al.
(författare)
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Photovoltaics with Piezoelectric Core-Shell Nanowires
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:4, s. 1108-1112
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Tidskriftsartikel (refereegranskat)abstract
- We report on a theoretical discovery of a generic piezoelectric held in strained core shell compound semiconductor nanowires. We show, using both an analytical model and numerical simulations based on fully electroelastically coupled continuum elasticity theory, that lattice-mismatch-induced strain in an epiraxial core shell nanowire gives rise to an internal electric held along the axis of the nanowire. This piezoelectric field results predominantly from atomic layer displacements along the nanowire axis within both the core and shell materials and can appear in both zinc blende and wurtzite crystalline core-shell nanowires. The effect can be employed to separate photon-generated electron hole pairs in the core shell nanowires and thus offers a new device concept for solar energy conversion.
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