| 1. |
|
|
| 2. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
-
Electroluminescence and photoluminescence excitation study of asymmetric coupled GaAs/AlxGa1-xAs V-groove quantum wires
- 2004
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:4
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied systems of asymmetric coupled GaAs V-groove quantum wires p-i-n diodes, in which the electrons and holes are injected into different wires. Despite the use of a 7 nm thick AlGaAs tunnel barrier, and although we demonstrate that holes tunnel more slowly than electrons, we observe a very efficient and fast tunneling between the quantum wires (QWR's). We attribute this to the achievement of a resonance between hole levels in the two QWR's. Photoluminescence excitation experiments are compared with accurate calculations of the excitonic absorption yielding a level of carrier transfer of nearly 100%. Temperature-dependent electroluminescence exhibits clear effects of tunneling up to room temperature but cannot distinguish separate electron/hole tunneling from exciton tunneling.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
-
Fractional-dimensional excitonic absorption theory applied to V-groove quantum wires
- 2004
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:15
-
Tidskriftsartikel (refereegranskat)abstract
- A fractional-dimensional approach is applied to a realistic V-groove quantum wire in order to calculate the excitonic absorption spectrum. An excellent agreement is obtained with much more computationally demanding models as well as with experimental photoluminescence excitation data. However, comparison with a full excitonic calculation reveals situations were the concept of fractional dimensions to some extent fails.
|
|
| 6. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
-
Strongly reduced exciton transfer between parallel quantum wires
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:10, s. 101108-101108-3
-
Tidskriftsartikel (refereegranskat)abstract
- Exciton transfer between two parallel GaAs V-groove quantum wires or two planar quantum wells separated by AlGaAs barriers ranging from 5.5 nm to 20 nm thickness is studied by photoluminescence and photoluminescence excitation spectroscopy. It is found that the transfer is strongly reduced between the widely spaced quantum wires as compared with quantum wells. This observation is supported by model calculations, which yield strong dimensionality dependence of the photon-exchange transfer.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Palmgren, Susanna, 1969-, et al.
(författare)
-
Polarization-resolved optical absorption in single V-groove quantum wires
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89, s. 191111-
-
Tidskriftsartikel (refereegranskat)abstract
- Optical transitions associated with all three linear polarization directions were investigated in single GaAs V-groove quantum wires of different wire thicknesses. This was accomplished by combining absorption measurements in V-groove waveguide geometry with surface-excited photoluminescence excitation spectroscopy. The observed transitions were identified with the aid of model calculations. It is shown that excitonic intersubband coupling should be accounted for in order to explain the optical transitions associated with confined light-hole-like states. The results are relevant for the design of efficient quantum wire waveguide modulators and lasers.
|
|
| 12. |
- Reichardt, H., et al.
(författare)
-
Influence of long-range substrate roughness on disorder in V-groove quantum wire structures
- 2006
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100, s. 123509-
-
Tidskriftsartikel (refereegranskat)abstract
- The observation and the interpretation of line splitting in photoluminescence and cathodoluminescence spectra of GaAs/AlGaAs V-groove quantum wires (QWRs) are reported. The QWR emission line splits into two peaks whose intensities oscillate systematically along the axis of the wire. Combining atomic force microscopy and cathodoluminescence measurements, we show a clear correlation between the surface topography of the V-groove and the individual peak intensities. We elucidate the relationship between the V-groove sidewall roughness and the shape at its bottom, and explain their impact on the QWR formation using a two-dimensional growth model accounting for self-limited growth in each V-groove domain. The influence of the long-range substrate roughness on the QWR spectral features is thus clarified. The study provides guidelines for improving QWR uniformity in order to achieve near-ideal model systems for one-dimensional semiconductors
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
- Weman, Helge, 1960-, et al.
(författare)
-
High internal quantum efficiency, narrow linewidth emission InGaAs/GaAs/AlGaAs quantum wire light-emitting diode
- 2002
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:15, s. 2839-2841
-
Tidskriftsartikel (refereegranskat)abstract
- High internal quantum efficiency (similar to60%), narrow linewidth (as narrow as 14 meV) exciton emission at room temperature has been obtained using strained InGaAs V-groove quantum wire (QWR) light-emitting diodes (LEDs). The high efficiency is achieved with the aid of selective carrier injection through self-ordered AlGaAs vertical quantum wells (VQWs), where the VQWs are separated from the InGaAs QWRs by thin GaAs spacer layers in order to reduce nonradiative recombination and inhomogeneous alloy broadening. Evidence for excitonic recombination in these LEDs up to RT is provided by measurements of the emission energy shifts at high magnetic fields.
|
|
| 16. |
|
|
| 17. |
- Weman, Helge, 1960-, et al.
(författare)
-
Semiconductor Quantum-Wires and Nano-Wires for optoelectronic Applications
- 2009
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 20:1, s. S94-S101
-
Tidskriftsartikel (refereegranskat)abstract
- Exciton transfer between two parallel GaAs V-groove quantum wires (QWRs) or two planar quantum wells (QWs) separated by AlGaAs barriers ranging from 5.5 nm to 20 nm thickness is studied by photoluminescence (PL) and PL excitation (PLE) spectroscopy. It is found that the transfer is strongly reduced between the widely spaced QWRs as compared with QWs. We have also investigated the optical absorption in single QWRs embedded in an AlGaAs V-shaped channel waveguide. Using a combination of PLE and absorption measurements we construct the full dependence of absorption spectra on the linear polarization. Our studies reveal the importance of inter-subband mixing in determining the energies of the light-hole-like transitions and thus the QWR absorption. Finally we present recent results on the fabrication and structural characterization of GaAs and GaP nanowires (NWs) grown by molecular beam epitaxy (MBE) on GaAs(111)B and Si(111) substrates, using Au-catalyzed vapor–liquid–solid growth technique. It is shown that, apart from optimizing the NW growth parameters, substrate material and the procedure for preparing the substrate before the MBE growth play an important role in controlling the NWs.
|
|
