« Previous
1
Next »
(8 hits, 1/1)
Showing
10, 25, 50, 100, 500, 1000, all papers per page.
Sort by:
last publication date,
older publication date,
last update date.
- 1. J.Am.Chem.Soc. 130, 48 (2008) , ACS , “Enhanced Ferromagnetism and Tunable Saturation Magnetization of Mn/C Codoped GaN Nanostructures Synthesized by Carbothermal Nitridation”, Zeyan Wang, Baibiao Huang, Lin Yu, Ying Dai, Peng Wang, Xiaoyan Qin, Xiaoyang Zhang, Jiyong Wei, Jie Zhan, Xiangyang Jing, Haixia Liu, and Myung-Hwan WhangboMn/C-codoped GaN nanostructures were synthesized by carbothermal nitridation with active charcoal as the carbon source. Nanostructures such as zigzag nanowires and nanoscrews were observed by varying the reaction time and the C/Ga molar ratio of the starting material used for the synthesis. The structures and morphologies of the as-grown samples were characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy measurements. The doping of both Mn and C in the GaN matrix was confirmed by X-ray photoelectron spectroscopy measurements, and the ferromagnetic properties of Mn/C-codoped GaN samples were confirmed by room-temperature magnetization measurements. The saturation magnetization of Mn/C-codoped GaN increases steadily with increasing C/Ga molar ratio of the starting material at a rate of ~0.023 emu/g per C/Ga molar ratio, and the ferromagnetism of Mn/C-codoped GaN can be stronger than that of Mn-doped GaN by a factor of ~40. A plausible growth mechanism was proposed, and the role of carbon codoping in tuning the morphology and ferromagnetic property was discussed. Our work suggests that carbon doping in the GaN matrix favors the N sites over the Ga sites, Mn/C-codoping in the GaN matrix is energetically favorable, and the C-codoping strongly enhances the preference of the FM coupling to the AFM coupling between the two doped Mn sites. These suggestions were probed on the basis of first-principles density functional theory electronic structure calculations for a number of model doped structures constructed with a 32-atom 2 × 2 × 2 supercell. (Read more)
- 2. Appl. Phys. Lett. 88, 161905 (2006) , “Defect characterization of Si-doped GaN films by a scanning near-field optical microscope-induced photoluminescence”, M. Yoshikawa, R. Sugie, M. Murakami, T. Matsunobe, K. Matsuda, and H. IshidaWe developed a tapping-mode-scanning near-field optical microscope to measure near-field photoluminescence (SNOM-PL) with nanometer spatial resolution using an ultraviolet laser, and we measured the defect distribution of a Si-doped GaN film. The obtained result was compared with one measured by... (Read more)
- 3. J. Appl. Phys. 100, 013501 (2006) , “Contactless electromodulation spectroscopy of AlGaN/GaN heterostructures with a two-dimensional electron gas: A comparison of photoreflectance and contactless electroreflectance”, R. Kudrawiec, M. Syperek, M. Motyka, J. Misiewicz, R. Paszkiewicz, B. Paszkiewicz, M. T?acza?aPhotoreflectance (PR) and contactless electroreflectance (CER) spectroscopies have been applied to study optical transitions in undoped and Si-doped AlGaN/GaN heterostructures at room temperature. Spectral features related to excitonic and band-to-band absorptions in GaN layer and band-to-band... (Read more)
- 4. Phys. Rev. B 74, 165202 (2006) , “Structural and electronic properties of Fe3+ and Fe2+ centers in GaN from optical and EPR experiments”, E. Malguth, A. Hoffmann, W. Gehlhoff, O. Gelhausen, M. R. Phillips, and X. XuThis work provides a consistent picture of the structural, optical, and electronic properties of Fe-doped GaN. A set of high-quality GaN crystals doped with Fe at concentrations ranging from 5×1017 cm3 to 2×1020 cm3 is... (Read more)
- 5. Phys. Rev. B 69, 115210 (2004) , “Optical and magnetic properties of Mn in bulk GaN”, A. Wolos, M. Palczewska, M. Zajac, J. Gosk, M. Kaminska, A. Twardowski, M. Bockowski, I. Grzegory, S. PorowskiWe report results of electron paramagnetic resonance, magnetization, and optical absorption studies of bulk GaN crystals doped with Mn and, for some samples, codoped with Mg acceptor. The experiments performed show that the charge state of the Mn ion in GaN depends on the Fermi level position in the... (Read more)
- 6. J. Appl. Phys. 93, 9697-9702 (2003) , “Growth and characterization of GaN:Mn epitaxial films”, T. Graf, M. Gjukic, M. Hermann, M. S. Brandt, M. Stutzmann, L. Görgens, J. B. Philipp, O. AmbacherThe oxidation states of Mn in epitaxial GaN films grown by plasma induced molecular beam epitaxy were investigated by electron spin resonance (ESR), elastic recoil detection, superconducting quantum interference device magnetization, and photothermal deflection spectroscopy measurements. Comparison... (Read more)
- 7. Mater. Sci. Eng. 93, 39-48 (2002) , “Characterization of nitrides by electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR)”, E. R. Glaser, W. E. Carlos, G. C. B. Braga, J. A. Freitas, Jr , W. J. Moore, B. V. Shanabrook, A. E. Wickenden, D. D. Koleske, R. L. Henry, M. W. Bayerl, M. S. Brandt, H. Obloh, P. Kozodoy, S. P. DenBaars, U. K. Mishra, S. Nakamura, E. Haus, J. S. Speck, J. E. Van Nostrand, M. A. Sanchez, E. Calleja, A. J. Ptak, T. H. Myers and R. J. MolnarWe will highlight our recent work on the properties of residual defects and dopants in GaN heteroepitaxial layers and on the nature of recombination from InGaN single quantum well (SQW) light emitting diodes (LEDs) through magnetic resonance techniques. Electron paramagnetic resonance (EPR) and... (Read more)
- 8. Mater. Sci. Eng. R 33, 135-207 (2001) , “Comprehensive characterization of hydride VPE grown GaN layers and templates”, H. MorkoçGaN community has recently recognized that it is imperative that the extended, and point defects in GaN and related materials, and the mechanisms for their formation are understood. This is a first and an important step, which must be followed by defect reduction before full implementation of this... (Read more)
« Previous
1
Next »
(8 hits, 1/1)
Showing
10, 25, 50, 100, 500, 1000, all papers per page.
Sort by:
last publication date,
older publication date,
last update date.
All papers (3399)
Updated at 2010-07-20 16:50:39
Updated at 2010-07-20 16:50:39
(view as: tree
,
cloud
)
1329 | untagged |
Materials
(111 tags)
Others(101 tags)
Technique
(46 tags)
Details
(591 tags)
Bond(35 tags)
Defect(interstitial)(18 tags)
Defect(vacancy)(15 tags)
Defect-type(19 tags)
Element(65 tags)
Energy(8 tags)
Isotope(56 tags)
Label(303 tags)
Sample(17 tags)
Spin(8 tags)
Symmetry(15 tags)