| 131. |
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| 132. |
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| 133. |
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| 134. |
- Zhao, QX, et al.
(författare)
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Deep-level emissions influenced by O and Zn implantations in ZnO
- 2005
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Ingår i: Applied Physics Letters. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 87:21
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Tidskriftsartikel (refereegranskat)abstract
- A set of bulk ZnO samples implanted with O and Zn at various densities were investigated by photoluminescence. The implantation concentration of O and Zn is varied between 1x10(17)/cm(3) and 5x10(19)/cm(3). The samples were thermally treated in an oxygen gas environment after the implantation. The results clearly show the influence of O and Zn implantations on the deep-level emission. By comparing the photoluminescence spectra for the samples with different implantations, we can conclude that the V-Zn is responsible to the observed deep-level emission. In addition, a novel transition at the emission energy of 3.08 eV at 77 K appears in the O-implanted sample with 5x10(19)/cm(3) implantation concentration. The novel emission is tentatively identified as O-antisite O-Zn.
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| 135. |
- Zhao, QX, et al.
(författare)
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Effects of nitrogen incorporation on the properties of GaInNAs/GaAs quantum well structures
- 2005
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 97:7
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Tidskriftsartikel (refereegranskat)abstract
- We report results from theoretical and experimental investigations of GaInNAs/GaAs quantum well structures. Optical transition energies for samples with different In and N concentrations were determined by photoluminescence measurements. The results show that the reduction of the ground-state transition energy by the introduction of N decreases with increasing In concentration. The experimental data are compared with calculations using the effective-mass approximation. Modifications of the band-gap energy due to N incorporation were accounted for using the two-level repulsion model. Proper effective-mass and band offset values, based on recent experimental work, were used. Calculated and measured transition energies show good agreement. The critical thickness, lattice constant, strain, and optical transition energies are discussed for GaInNAs/GaAs quantum well structures tuned for emission at 1.3 and 1.55 mu m, in particular. Such a simple model, within the effective-mass approximation, is a very useful guide for device design. (C) 2005 American Institute of Physics.
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| 136. |
- Zhao, QX, et al.
(författare)
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Nonradiative centers in InAs dots grown on GaAs substrates for 1.3 mu m emission
- 2003
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Ingår i: Physics Letters A. - : Elsevier Science B.V., Amsterdam.. - 0375-9601 .- 1873-2429. ; 315:02-Jan, s. 150-155
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Tidskriftsartikel (refereegranskat)abstract
- Nonradiative centers in InAs dots grown on GaAs substrates are investigated in this study. The emission from InAs dots close to 1.3 mum is monitored under different excitation densities and different excitation energy. The used samples were also treated by hydrogen plasma in order to suppress the nonradiative centers. The purpose of this work is to study how nonradiative centers influence the efficiency of InAs dots emission and whether the nonradiative centers can be reduced. Our results clearly illustrate that there indeed exist nonradiative centers, both at the interface between the InAs dots and surrounding layers and in the GaAs layers, which can be suppressed by H-treatments. A technique to estimate relative amount of nonradiative centers is also discussed.
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| 137. |
- Zhao, QX, et al.
(författare)
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Strong enhancement of the photoluminescence-efficiency from InAs quantum dots
- 2003
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 93:3, s. 1533-1536
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Tidskriftsartikel (refereegranskat)abstract
- InAs quantum dots (QDs) have been investigated using optical spectroscopy, in order to understand the experimental observation of strong enhancement of their photoluminescence efficiency. When a tunneling barrier is introduced between the, InAs layer and the GaAs cap layer, the intensity of the InAs QD emission increases by more than an order of magnitude at the excitation density of 60 W/cm(2). The enhancement of the optical recombination efficiency is due to the suppression of the nonradiative transitions in the wetting layer. The strong enhancement of the InAs emission can lead to an increase in the optical gain of the InAs laser structure
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| 138. |
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| 139. |
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| 140. |
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