| 1. |
- Berggren, Magnus, et al.
(författare)
-
Controlling inter-chain and intra-chain excitations of a poly(thiophene) derivative in thin films
- 1999
-
Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 304:1-2, s. 84-90
-
Tidskriftsartikel (refereegranskat)abstract
- The decay of photoexcitations in polythiophene chains has been studied in solid solutions of the polymer from room temperature to 4 K. A strong blue shift of the emission spectrum is observed in the polymer blend, as compared to the homopolymer. Dispersion of the polythiophene suppresses the non-radiative processes, which are suggested to be correlated to close contacts of polymer chains. Quantum chemistry modeling of the excited state distributed on two chains corroborate this conclusion.
|
|
| 2. |
- Gorji, Sepideh, et al.
(författare)
-
Self-catalyzed MBE grown GaAs/GaAsxSb1-x core-shell nanowires in ZB and WZ crystal structures
- 2013
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 24:40
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the growth of self-catalyzed GaAs/GaAsxSb1-x core-shell nanowires directly on Si(111) substrates by molecular beam epitaxy. The compositions of the GaAsxSb1-x shells are tuned in a wide range where the Sb-content is varied from 10 to similar to 70%, covering the miscibility gap. In addition, the GaAsxSb1-x shells are grown on both zinc blende (ZB) and wurtzite (WZ) crystal structures. Morphological and structural characterizations of the grown nanowires indicate successful transfer of the GaAs core crystal structure to the GaAsxSb1-x shells for both ZB and WZ nanowires, with slower shell growth rate on the WZ segments.
|
|
| 3. |
|
|
| 4. |
- 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.
|
|
| 5. |
- Karlsson, Fredrik, 1974-, et al.
(författare)
-
Electrolummescence of asymmetric coupled GaAs/AlGaAs V-groove quantum wires
- 2003
-
Ingår i: Institute of Physics Conference Series. - 0951-3248 .- 2154-6630. ; 174, s. 183-186
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied systems of asymmetric coupled GaAs V-groove quantum wires, in which the electrons and holes are injected into different wires. Our experimental results indicate efficient electron and hole tunneling, despite a 7 nm thick AlGaAs tunnel barrier. Temperature dependent electroluminescence exhibit clear effects of tunneling up to room temperature but cannot distinguish electron/hole tunneling from exciton tunneling.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- 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.
|
|
| 9. |
- 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.
|
|
| 10. |
|
|
