| 1. |
- Li, Z-F, et al.
(författare)
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Determination of carrier-transfer length from side-wall quantum well to quantum wire by micro-photoluminescence scanning
- 2003
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Ingår i: Journal of Electronic Materials. - : Springer Science Business Media. - 0361-5235 .- 1543-186X. ; 32:8, s. 913-916
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Tidskriftsartikel (refereegranskat)abstract
- Micro-photoluminescence (mu-PL) line scanning across a single V-groove, GaAs/AlGaAs quantum wire (QWR) has been performed at room temperature, revealing a clear spatial-dependence of the PL. After fitting each PL spectrum by multi-Gaussian line shapes, intensity profiles of each PL component from confined structures have been obtained as functions of the scanning position. The PL quenching of a side-wall quantum well (SQWL) has been recognized in a certain area in the vicinity of the QWR and is interpreted by carrier transfer into the QWR within effective transfer length. By simulating the carrier-transfer process from SQWL to QWR as a convolution of a step function for carrier distribution and a Gaussian function for exciting laser irradiance, the effective transfer length of about 1.8+/-0.3 mum has, therefore, been concluded.
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| 2. |
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| 3. |
- lI, M. X.D., et al.
(författare)
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Two-mesh refinement indicators and adaptivity in non-linear explicit finite element analysis of shells using LS-DYNA
- 2000
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Ingår i: International Journal for Numerical Methods in Engineering. - 0029-5981 .- 1097-0207. ; 16:11, s. 785-800
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Tidskriftsartikel (refereegranskat)abstract
- Two-mesh refinement indicators based on the gradients of effective stresses and effective plastic strains, respectively, are proposed for adaptive finite element analysis of the large deformation, materially non-linear dynamic response of shells. The refinement strategy consists of equi-distributing the variation of stresses or plastic strains over the elements of the mesh. A program module for implementing these refinement indicators has been developed and coupled with the general non-linear finite element explicit code LS-DYNA. Numerical examples including both material and geometric non-linearities are presented. It is shown that these indicators can effectively identify those finite elements, which have high gradients of stresses and strains so that the mesh is refined in the region's undergoing the most severe deformations.
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| 4. |
- 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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| 5. |
- Zheng, W.T., et al.
(författare)
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Chemical bonding, structure, and hardness of carbon nitride thin films
- 2000
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Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 9:9-10, s. 1790-1794
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Carbon nitride films are deposited on Si(001) substrates by reactive d.c. magnetron sputtering graphite in a pure N2 discharge. The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS), and the hardness was evaluated using nanoindentation experiments. The structure and hardness for the films are dependent on the substrate temperature (T(s)). FTIR and NEXAFS spectra show that N atoms are bound to sp1, sp2 and sp3 hybridized C atoms, and the intensity of p(*) resonance for C1s NEXAFS spectra is the lowest for the film grown at T(s) = 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the structure and hardness of carbon nitride films is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.Carbon nitride films are deposited on Si(001) substrates by reactive d.c. magnetron sputtering graphite in a pure N2 discharge. The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS), and the hardness was evaluated using nanoindentation experiments. The structure and hardness for the films are dependent on the substrate temperature (Ts). FTIR and NEXAFS spectra show that N atoms are bound to sp1, sp2 and sp3 hybridized C atoms, and the intensity of p* resonance for C1s NEXAFS spectra is the lowest for the film grown at Ts = 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the structure and hardness of carbon nitride films is discussed.
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