Papers by Keyword: Photoluminescence (PL)

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Authors: M.D. Efremov, Vladimir A. Volodin, D.V. Marin, Sofia A. Arzhannikova, M.G. Ivanov, S.V. Gorajnov, A.I. Korchagin, V.V. Cherepkov, A.V. Lavrukhin, S.N. Fadeev, R.A. Salimov, S.P. Bardakhanov
Abstract: Silicon nanopowders were produced using electron-beam-induced evaporation of bulk silicon ingots in various gas atmosphere. Optical properties of the nanopowders were studied with the use of photoluminescence and Raman spectroscopy techniques. Photoluminescence peaks in the visible region of the spectrum have been detected at room temperature in silicon nanopowders, produced in argon gas atmosphere. Strong short-wavelength shift of the photoluminescence peaks can be result of quantum confinement effect for electrons and holes in small silicon nanocrystals (down to 2 nm in diameter). The size of silicon nanocrystals was estimated from Raman spectroscopy data. The calculated in frame of effective mass model optical gaps for silicon nanocrystals of spherical shape are in good correlation with experimental photoluminescence data. The attempts of deposition of silicon nanocrystal films from the nanopowders on silicon substrates were carried out.
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Authors: Wen Teng Chang, Yu Ting Chen, Chung Chin Kuo
Abstract: Five-period hydrogenated silicon carbide (SiC) multiple quantum wells with silicon dioxide (SiO2) or silicon nitride (SiN) dielectric that were synthesized by high density plasma chemical vapor deposition were studied using photoluminescence (PL) spectroscopy to understand its blue shift. Rapid thermal annealing induced significant blue shifting in the PL spectra after fluorine ion implantation due to crystallization. The thinning of the SiC causes blue shift due to the quantum confinement effect. The higher PL intensity of the amorphous SiC:H in SiO2 than in SiC/SiN may be attributed to the high number of non-radiative sites on its surface. Annealing with nitrogen may cause impurities in SiC/SiO2, thereby broadening the PL peak.
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Authors: Zhen Ming Chu, Yan Xia Li, Xu Sheng Wang, Xi Yao
Abstract: This paper studied the mechanoluminescence of the CaAl2Si2O8:Eu2+x, Dy3+y phosphors. The crystal structure, photoluminescence (PL) and mechanoluminescent intensity of the phosphors were investigated. The emission peak of CaAl2Si2O8: Eux2+ had a redshift from 418 nm to 428 nm due to the increase of the crystal filed intensity around Eu2+ with the increase of Eu2+ ion content. The ML (mechanoluminescence) emission of CaAl2Si2O8:Eu0.01and CaAl2Si2O8:Eu2+0.01, Dy3+0.02 can be seen by the naked eyeswhen compressive loads were appliedon the samples. Whats more, the addition of Dy3+can increase the ML intensity of CaAl2Si2O8:Eu0.01. The ML and PL spectra of the sample CaAl2Si2O8:Eu2+0.01, Dy3+0.02 are identical, located at 428 nm.
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Authors: Hong Wu Zhang, Hiroshi Yamada, Nao Terasaki, Chao Nan Xu
Abstract: We have revealed that SrCaMgSi2O7:Eu phosphors emits blue-greenish light under the application of a mechanical stress, called as mechanoluminescence (ML). The ML showed a similar spectrum as photoluminescence, which indicated that ML is emitted from the same center of Eu2+ ions as PL. Such a blue-greenish light of ML emission can be seen by the naked eye when pressing the sample. In addition, the ML intensity of SrCaMgSi2O7:Eu proportionally increased with the increase of mechanical load.
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Authors: T. Egilsson, Anne Henry, Ivan G. Ivanov, J. Lennart Lindström, Erik Janzén
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Authors: Aidhia Rahmi, Akrajas Ali Umar, Muhamad Mat Salleh, Burhanuddin Yeop Majlis, Munetaka Oyama
Abstract: This paper reports the preparation of exceptionally high brightness CdTe quantum dots (QDs) that gives emission in the range of green to red by simply prepared them in a binary mixture of octadecyl phosphonic acid (ODPA) and oleic acid (OA) surfactants. By easy controlling the ratio between the two surfactants in the reaction, the QDs with unique emission, high -brightness and -quantum yield (QY), ca. 63, 87 and 89% for green, yellow and red QDs respectively, can be obtained. Owing to their unique PL and high QY, the CdTe QDs should find an extensive uses in the currently existing applications.
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Authors: A.N. Safonov, Edward C. Lightowlers, Gordon Davies
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Authors: Li Min An, Xuan Lin Chen, Xue Ting Han, Jie Yi, Chun Xia Liu, Wen Yu An, Yu Qiu Qu, Jian Guang Chi, Hong Wei, Kai Yue Qi, Ya Nan Wen, Qiang Wang, Wei Gang Zhou, Hong An Ye, Zhuo Sun
Abstract: CdSe/ZnO core/shell semiconductor nanocrystals which show high luminescence quantum yield have been synthesized through a simple routine without the use of any pyrophoric organometallic precursors. Transmission electron microscope image demonstrates the shape, monodispersity, average size, size distribution and core-shell structure of CdSe/ZnO nanocrystals. We use a combination of X-ray diffraction, UV-Vis absorption spectroscopy and photoluminescence to analyze the core/shell nanocrystals and determine their chemical composition, optical character and internal structure.
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Authors: Ivan G. Ivanov, Ulf Lindefelt, Anne Henry, T. Egilsson, Olof Kordina, Erik Janzén
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Authors: Ali Ghaderi, Semih Senkader
Abstract: A major performance limiting factor of multicrystalline silicon wafers is structural defects, mainly dislocations, reducing solar cell efficiency. Dislocations are formed during crystallisation process. Characterization of dislocation-content is necessary both to optimise the crystallisation and to eliminate bad wafers before cell processing. We developed two techniques to characterise dislocations: conventional etch-pit counting modified for full size wafers using a new etch-recipe and a novel etch-pit counting algorithm. Secondly we developed a technique to estimate the dislocation content directly from photoluminescence images of as-cut wafers.
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