| 1. |
- Lu, W, et al.
(author)
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Enhancement of room-temperature photoluminescence in InAs quantum dots
- 2003
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In: Applied Physics Letters. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 83:21, s. 4300-4302
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Journal article (peer-reviewed)abstract
- We report pronounced enhancement of room-temperature photoluminescence up to 80-fold induced by proton implantation and the rapid thermal annealing process in a multilayer InAs/GaAs quantum-dot structure. This effect is studied by a combination of material methods and resulted from both proton passivation and carrier capture enhancement effects. The maximum photoluminescence peak shift is about 23 meV, resulting from the intermixing of quantum dots. Linear dependence behavior as observed for both the nonradiative recombination time and carrier relaxation time on the ion-implantation dose. Maximum enhancement of the photoluminescence is observed for a proton implantation dose of 1.0x10(14) cm(-2) followed by rapid thermal annealing at 700 degreesC. These effects will be useful for quantum dot optoelectronic devices.
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| 2. |
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| 3. |
- Fu, Ying, 1964, et al.
(author)
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Photoluminescence spectra of doped GaAs films
- 2004
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In: Applied Physics A. - : Springer Science Business Media. - 0947-8396 .- 1432-0630. ; 79:3, s. 619-623
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Journal article (peer-reviewed)abstract
- We have studied the dependence of the photoluminescence (PL) spectrum on the doping level and the film thickness of n-GaAs thin films, both experimentally and theoretically. It has been shown theoretically that modification of the PL spectrum of p-type material by p-type doping is very small due to the large valence-band hole effective mass. The PL spectrum of n-type material is affected by two factors: (1) the electron concentration which determines the Fermi level in the material; (2) the thickness of the film due to re-absorption of the PL signal. For the n-type GaAs thin films under current investigation, the doping level as well as the film thickness can be very well calibrated by the PL spectrum when the doping level is less than 2 x 10(18) cm(-3) and the film thickness is in the range of the penetration length of the PL excitation laser.
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| 4. |
- Ji, Xiaoyan, et al.
(author)
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Determination of dissolution kinetics of K2SO4 crystal with ion selective electrode
- 2001
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In: Chemical Engineering Science. - 0009-2509 .- 1873-4405. ; 56, s. 7017-7024
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Journal article (peer-reviewed)abstract
- The dissolution kinetics of potassium sulfate crystals was studied and the effects of hydrodynamic situation and temperature on the dissolution were investigated. The dissolution was determined by measuring the change of electromotive force (E) with the potassium ion selective electrode. From the values of E, the concentration of K+ was calculated combined with an activity coefficient model. The results are accurate and rapid, the maximum deviation is less than 2%. Theory, developed for constant bulk concentration in a rotating disk system, was modified in order to analyze the general grain dissolution process. Normal distribution was introduced in calculating the area of crystals in order to obtain reliable dissolution rate. Using the modified theory diffusion rate constant, equilibrium exchange rate constant and thickness of diffusion layer were obtained. It is found that the diffusion rate constants increase while the thickness of diffusion layer decreases with the increase of temperature and stirring speed; the equilibrium exchange rate is dependent on bulk concentration.
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| 5. |
- Liu, C, et al.
(author)
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The study of dissolution kinetics of K2SO4 crystal in aqueous ethanol solutions with a statistical rate theory
- 2004
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In: Chinese Journal of Chemical Engineering. - 1004-9541 .- 2210-321X. ; 12, s. 128-130
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Journal article (peer-reviewed)abstract
- Dissolution kinetics of K2SO4 crystal in aqueous ethanol solutions was studied on-line with ion selective electrode. The concentration of K2SO4 was calculated from the determined electromotive force in which the activity coefficient of components in the liquid phase was calculated with the Pitzer equation. Dissolution kinetic parameters in the modified statistical rate theory were regressed. The correlation results show that dissolution rate of K2SO4 is slower in aqueous ethanol solutions than that in aqueous solutions. The two most important reasons are as follows: (1) The solubility Of K2SO4 in aqueous ethanol solutions is lower than that in aqueous solutions, which causes a decrease of the driving force of mass transfer. (2) The process of surface reaction Of K2SO4 became slower due to the addition of ethanol, so that the whole process is mainly dominated by the surface reaction instead of mass transfer.
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