| 1. |
- Ben Sedrine, N., et al.
(author)
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Effect of nitrogen on the GaAs0.9-xNxSb0.1 dielectric function from the near-infrared to the ultraviolet
- 2010
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In: Applied Physics Letters. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 97:20, s. 201903-
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Journal article (peer-reviewed)abstract
- We study the effect of nitrogen on the GaAs0.9-xNxSb0.1 (x = 0.00, 0.65%, 1.06%, 1.45%, and 1.90%) alloy dielectric function by spectroscopic ellipsometry in the energy range from 0.73 to 4.75 eV. The compositional dependences of the critical points energies for the GaAs0.9-xNxSb0.1 are obtained. In addition to the GaAs intrinsic transitions E-1, E-1+ Delta(1), and E-0, the nitrogen-induced Gamma-point optical transitions E-0 and E+, together with a third transition E-#, are identified. We find that with increasing the N content, the E-0 transition shifts to lower energies while the E+ and (E)# transitions shift to higher energies. We suggest that the origin of the E-0, E+, and E-# transitions may be explained by the double band anticrossing (BAC) model, consisting of a conduction BAC model and a valence BAC model.
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| 2. |
- Ben Sedrine, N, et al.
(author)
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Optical properties of GaAs0.9-xNxSb0.1 alloy films studied by spectroscopic ellipsometry
- 2011
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In: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND. - 0040-6090. ; 519:9, s. 2838-2842
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Journal article (peer-reviewed)abstract
- Spectroscopic ellipsometry from 0.73 to 4.75 eV was used to study the optical properties of epitaxial GaAs0.9-xNxSb0.1 layers with x=0.00, 0.65, 1.06, 1.45 and 1.90%. The ellipsometric experimental spectra were fitted using a multilayer model employing the model dielectric function to describe the GaAs0.9-xNxSb0.1 optical response. We have identified the Gamma-point E-0, E+, and E-# transitions of GaAs0.9-xNxSb0.1 and have determined the effect of nitrogen on the respective transition energies. We have demonstrated that a lower N content can provide an equal E+-E-0 energy splitting for GaAs0.9-xNxSb0.1 with respect to GaAs1-xNx.
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| 3. |
- Misiewicz, J., et al.
(author)
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Photoreflectance investigations of the energy level structure in GaInNAs-based quantum wells
- 2004
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In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 16:31, s. S3071-S3094
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Journal article (peer-reviewed)abstract
- In this paper, we present the application of photoreflectance (PR) spectroscopy to investigate the energy level structure of GaInNAs-based quantum wells (QWs). Series of single GaInNAs/GaAs QWs with different nitrogen and indium contents are analysed. The electron effective mass (m(e)(*)) and conduction e band offset (Q(C)) are determined and compared with the literature data. The Q(C) in GaInNAs/GaAs system in the range of investigated GaInNAs content (28-41% of In, 0.3-5.3% of N) has been found to be almost the same as for GaInAs/GaAs system, i.e. Q(C) approximate to 0.8. In addition, the energy level structure for the step-like GaInNAs/Ga(In)NAs/GaAs QWs tailored at 1.3 and 1.55 mum and the Sb-containing Ga(In)NAs/GaAs QWs is investigated. Also, the character of PR transitions, the influence of rapid thermal annealing (RTA) on the energy level structure, and the influence of the carrier localization effect on the efficiency of PR photomodulation are discussed.
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| 4. |
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| 5. |
- Wang, Xingjun, et al.
(author)
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Efficient Spin Filter Based on Non-Magnetic Semiconductor GaNAs
- 2009
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In: Integrated Photonics and Nanophotonics Research and Applications/Nonlinear Optics/Slow and Fast Light. - 9781557528735 ; , s. IWD4-
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Conference paper (peer-reviewed)abstract
- We provide experimental demonstration of a novel defect-engineered, efficient and switchable spin filter from GaNAs to generate, amplify and detect electron spin polarization at room temperature without a magnetic material or external magnetic fields.
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| 6. |
- Wang, Xingjun, 1972-, et al.
(author)
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Generating strong electron spin polarization at room temperature in GaNAs via spin-dependent recombination
- 2008
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In: 5th International Conference on Physics and Applications of Spin-related Phenomena in Semiconductors PASPS V,2008.
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Conference paper (other academic/artistic)abstract
- The issues of generating and maintaining carrier spin polarization in semiconductors have attracted intense research efforts, not only due to their importance for future applications in spintronics but also due to the intriguing physics underpinning spin-dependent phenomena. Entering the family of semiconductors that exhibit attractive spin-dependent properties, Ga(In)NAs was most recently found to exhibit strong spin polarization of conducting electrons at room temperature upon N incorporation with an extremely long apparent spin lifetime. In this work we have uncovered the origin of the astonishing effect as being due to strong spin dependent recombination (SDR) via defects, by a combination of optical orientation and optically detected magnetic resonance (ODMR) studies. We were able to identify Ga self-interstitials and an As antisite complex to be the dominant defects participating in the SDR process. The involvement of these defects were unambiguously established by their unique spin-resonance signatures derived from the hyperfine interaction between the localized unpaired electron spin and nuclear spins (I=3/2) of the As and Ga atom - the core of the defects. These defects dominate in carrier capture and recombination leading to the observed strong dynamic polarization of electron spins. Further confirmation was found by the effects of growth conditions and post-growth treatments on the defect density that were closely correlated with the electron spin polarization.
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| 7. |
- Wang, Xingjun, et al.
(author)
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Room-temperature defect-engineered spin filter based on a non-magnetic semiconductor.
- 2009
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In: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 8:3, s. 198-202
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Journal article (peer-reviewed)abstract
- Generating, manipulating and detecting electron spin polarization and coherence at room temperature is at the heart of future spintronics and spin-based quantum information technology. Spin filtering, which is a key issue for spintronic applications, has been demonstrated by using ferromagnetic metals, diluted magnetic semiconductors, quantum point contacts, quantum dots, carbon nanotubes, multiferroics and so on. This filtering effect was so far restricted to a limited efficiency and primarily at low temperatures or under a magnetic field. Here, we provide direct and unambiguous experimental proof that an electron-spin-polarized defect, such as a Ga(i) self-interstitial in dilute nitride GaNAs, can effectively deplete conduction electrons with an opposite spin orientation and can thus turn the non-magnetic semiconductor into an efficient spin filter operating at room temperature and zero magnetic field. This work shows the potential of such defect-engineered, switchable spin filters as an attractive alternative to generate, amplify and detect electron spin polarization at room temperature without a magnetic material or external magnetic fields.
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| 8. |
- Weman, Helge, 1960-, et al.
(author)
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Semiconductor Quantum-Wires and Nano-Wires for optoelectronic Applications
- 2009
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In: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 20:1, s. S94-S101
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Journal article (peer-reviewed)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.
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| 9. |
- Zhao, F, et al.
(author)
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Electron spin control in dilute nitride semiconductors
- 2009
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In: JOURNAL OF PHYSICS-CONDENSED MATTER. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 21:17, s. 174211-
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Journal article (peer-reviewed)abstract
- We report on a study of spin-dependent recombination processes (SDR) for conduction band electrons on deep paramagnetic centers in a series of GaAs1-yNy epilayers by time-resolved optical orientation experiments. We demonstrate that this dilute nitride compound can be used as an effective electron spin filter under a polarized optical excitation of appropriate intensity. This optimum intensity can moreover be controlled by adjusting the nitrogen composition in the layer.
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