Papers by Keyword: Photoluminescence (PL)

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Authors: V. Dixit, H.F. Liu, N. Xiang
Abstract: Blueshifts of photoluminescence (PL) peak wavelength from GaInNAs/GaAs quantum well (QW) at various annealing temperatures have been studied. Our results indicate that as-grown GaInNAs/GaAs QW sample has N-Ga3In1 phase, which changes to a mixture of N-Ga3In1 and NGa2In2 after annealing. The activation energy characterized for short range order is 2.38 eV, which is smaller than that for the diffusion process (3.196 eV). This indicates that the short range order is the dominant mechanism for PL blueshift at relatively low annealing temperature and for short time annealing.
Authors: Chang Fa Li, Ji Guang Li
Abstract: In this work, hexagonal solid solutions of (Gd0.95Eu0.05)(OH)3 with two distinctive morphologies of nanorods and nanotubes were successfully synthesized via hydrothermal treatment of mixed nitrate solutions in the presence of ammonium hydroxide. The hydroxide samples exhibited characteristic Eu3+ photoluminescence through the energy transfer from Gd3+ to Eu3+ and the self-excitation of Eu3+. The hydroxide precursors transformed into cubic (Gd0.95Eu0.05)2O3 at ~500 °C via an intermediate monoclinic (Gd0.95Eu0.05)OOH phase, and the Eu3+ coordination accordingly experienced symmetry changes from D3h to C2v, and then to C2/S6. The cubic (Gd0.95Eu0.05)2O3 well retained the original morphologies of their polycrystalline precursors and exhibited a single-crystalline character at 1000 °C. Greatly enhanced photoluminescence (~5000 times that of the hydroxides) was observed for the phase conversion.
Authors: Anne Henry, Xun Li, Henrik Jacobson, Sven Andersson, Alexandre Boulle, Didier Chaussende, Erik Janzén
Abstract: The growth of 3C-SiC on hexagonal polytype is addressed and a brief review is given for various growth techniques. The Chemical Vapor Deposition is shown as a suitable technique to grow single domain 3C epilayers on 4H-SiC substrate and a 12.5 µm thick layer is demonstrated; even thicker layers have been obtained. Various characterization techniques including optical microscopy, X-ray techniques and photoluminescence are compared for the evaluation of the crystal quality and purity of the layers.
Authors: Takashi Aigo, Wataru Ito, Hiroshi Tsuge, Hirokatsu Yashiro, Masakazu Katsuno, Tatsuo Fujimoto, Wataru Ohashi
Abstract: 4H-SiC epitaxial growth on 2˚ off-axis substrates using trichlorosilane (TCS) is presented. Good surface morphology was obtained for epilayers with C/Si ratios of 0.6 and 0.8 at a growth temperature of 1600°C. The triangle defect density was reduced to a level below 5 cm-2 at 1600°C and below 1 cm-2 at 1625°C for a C/Si ratio of 0.8. Photoluminescence (PL) measurements were carried out with band-pass filters of 420 nm, 460 nm, and 480 nm to detect stacking faults. A stacking fault density of below 5 cm-2 was achieved at 1600°C and 1625°C with a C/Si ratio of 0.8. The optimal conditions for TCS growth were a C/Si ratio of 0.8 and a growth temperature of 1600°C. The evaluation of stacking faults and etch pit density indicated that the use of 2˚ off-axis substrates and TCS is effective for reducing basal plane dislocations. Comparing these results to those using silane (SiH4) with HCl added, it was demonstrated that TCS is much more suitable for obtaining high-quality epilayers on 2º off-axis substrates.
Authors: Qiang Xu, Hua Yang Sun, Cheng Chen, Ling Yun Jang, E. Rusli, Suwan P. Mendis, Chin Che Tin, Zhi Ren Qiu, Zheng Yun Wu, Chee Wee Liu, Zhe Chuan Feng
Abstract: Synchrotron radiation X-ray absorption and UV 325 nm excitation Raman scattering- photoluminescence (PL) have been employed to investigate a series of 4H-SiC wafers, including bulk, epitaxial single or multiple layer structures by chemical vapor deposition. Significant results on the atomic bonding and PL-Raman properties are obtained from these comparative studies.
Authors: Teddy Robert, Sandrine Juillaguet, Maya Marinova, Thierry Chassagne, Ioannis Tsiaousis, N. Frangis, Efstathios K. Polychroniadis, Jean Camassel
Abstract: The electronic structure of in-grown 8H stacking faults in 4H-SiC matrix has been investigated in detail. After assessment of the structural properties by high resolution transmission electron microscopy, we focus on the electronic structure. We show that one unit cell of 8H does not behave like a single type-II quantum well but, rather, like two type-II quantum wells of 3C coupled by a thin hexagonal barrier. Using a transfer matrix method, we compute the corresponding transition energies, taking into account the effect of the valence band offset and built-in electric field. A good agreement is found with the experimental data collected from low temperature photoluminescence spectroscopy.
Authors: W. Sullivan, John W. Steeds, Hans Jürgen von Bardeleben, J.L. Cantin
Abstract: Several 4H SiC samples have been electron-irradiated at near threshold energies at low fluence, either along the [0001] or [000-1] direction. PL and EPR techniques have been used to investigate the dependence of the beam direction on defect generation and, together with a sample irradiated at a higher fluence, to correlate differences brought about by irradiating with a change in electron fluence. Attempts are made to correlate the information derived from the two techniques.
Authors: Zhi Bing Xu, Yi Wang
Abstract: ZnO nanoparticles have been fabricated with cation resins templates by thermal decomposition reaction. TEM and XRD showed the ZnO nanoparticles synthesized have an average diameter of 46.5 nm with sphere-shaped. One strong green-light emission peak at 530 nm was observed.
Authors: K.J. Chang, Sun Ghil Lee
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