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- Blom, Anders, et al.
(författare)
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Resonant states in doped quantum wells
- 2003
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Ingår i: Physica Status Solidi. B: Basic Research. - : Wiley. - 0370-1972. ; 235:1, s. 85-88
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Tidskriftsartikel (refereegranskat)abstract
- Resonant states can have an important influence on the electronic transport, noise and optical properties of heterostructure devices. We have used a non-variational method to study the resonant states formed by shallow donors inside and outside of quantum wells. The method allows us the evaluation of the position and the width (lifetime) of the resonant states and also of matrix elements such as optical transition probabilities. When the width is compared to results from the approach of resolvent operators, a quantitative difference is found, which we attribute to the neglected intraband scattering in the latter method. We also show how the impurity states, localized and resonant, evolve as the donor is moved into the quantum well from an originally infinite distance.
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| 2. |
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| 3. |
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| 4. |
- Jin, Kui-Juan, et al.
(författare)
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Terahertz frequency radiation from Bloch oscillations in GaAs/Al0.3Ga0.7As superlattices
- 2003
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 68:15: 153315
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Tidskriftsartikel (refereegranskat)abstract
- We have performed a joint theoretical and experimental study to investigate the terahertz radiation from Bloch oscillations in a GaAs/Al0.3Ga0.7As superlattice under the condition that there is no Zener tunneling. The total radiation intensity has been calculated with a semiclassical approach in the low field regime where the Wannier-Stark ladder (WSL) cannot be resolved, and with an exact numerical solution in the high field regime where the WSL is well formed. With an adjustment of the intensity units, without fitting material parameters, the calculated results agree almost perfectly with the measured data given in arbitrary units. Consequently, our work gives convincing evidence that the measured THz radiation is due to the Bloch oscillations.
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| 5. |
- Zheng, WT, et al.
(författare)
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Chemical bonding in carbon nitride films studied by X-ray spectroscopies
- 2001
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Ingår i: DIAMOND AND RELATED MATERIALS. - : ELSEVIER SCIENCE SA. - 0925-9635. ; 10:9-10, s. 1897-1900 Language: English
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride films are deposited using dc magnetron sputtering in a N-2 discharge. The nature of chemical bonding of the films is investigated using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray emission spectros
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| 6. |
- Zheng, W.T., et al.
(författare)
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Chemical bonding in carbon nitride films studied by X-ray spectroscopies
- 2001
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Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 10:9-10, s. 1897-1900
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride films are deposited using dc magnetron sputtering in a N2 discharge. The nature of chemical bonding of the films is investigated using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray emission spectroscopy. X-Ray photoelectron spectroscopy spectra show that N1s binding states depend on substrate temperature, in which two pronounced peaks can be observed. The near edge X-ray absorption fine structure at C1s and N1s exhibits a similar absorption profile in the p* resonance region, but the s* resonance is sharper in the N1s spectra. Resonant N K-emission spectra show a strong dependence on excitation photo energies. Compared XPS N1s spectra with recent theoretical calculations by Johansson and Stafstrom, two main nitrogen sites are assigned in which N bound to sp3 hybridized C and sp2 hybridized C, respectively. The correlation of X-ray photoelectron, X-ray absorption, and X-ray emission spectra for N in carbon nitride films is also discussed. © 2001 Elsevier Science B.V. All rights reserved.
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