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- 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. Phys. Rev. B 77, 195204 (2008) , “Identification of antisite carbon split-interstitial defects in 4H-SiC”, J. W. Steeds, W. SullivanA rich variety of optical centers with high energy local vibrational modes has been found in electron-irradiated 4H-SiC in both the as-irradiated and annealed states. These energies have been measured and the annealing dependence of the optical centers has been investigated by low-temperature... (Read more)
- 3. Phys. Rev. B 77, 195203 (2008) , “Creation and identification of the two spin states of dicarbon antisite defects in 4H-SiC”, J. W. Steeds, W. Sullivan, S. A. Furkert, G. A. Evans, P. J. WellmannThis paper deals with the positive identification by low-temperature photoluminescence microspectroscopy of the two spin states of the dicarbon antisites in 4H-SiC. The defects are created by high-dose electron irradiation at room temperature or by subsequent exposure to intense 325 nm radiation at... (Read more)
- 4. Phys. Rev. B 77, 085120 (2008) , “Identification of the carbon antisite in SiC: EPR of 13C enriched crystals”, Pavel G. Baranov, Ivan V. Ilyin, Alexandra A. Soltamova, and Eugene N. MokhovAn electron paramagnetic resonance spectrum with axial symmetry along c axis, spin S=1/2 and strong hyperfine interaction with one carbon atom has been observed in neutron-irradiated and annealed 6H-SiC, 13C isotope enriched. The 13C concentration was... (Read more)
- 5. phys. stat. sol. (b) 245, 1298-1314 (2008) , “EPR identification of intrinsic defects in SiC”, J. Isoya, T. Umeda, N. Mizuochi, N. T. Son, E. Janzen, T. OhshimaThe structure determination of intrinsic defects in 4H-SiC, 6H-SiC, and 3C-SiC by means of EPR is based on measuring the angular dependence of the 29Si/13C hyperfine (HF) satellite lines, from which spin densities, sp-hybrid ratio, and p-orbital direction can be determined over... (Read more)Si SiC diamond| EPR Theory electron-irradiation thermal-meas./anneal-exp.| +1 -1 0(neutral) 1.0eV~ 13C 29Si C1h C3v Carbon Csi D2d EI5/6 HEI1 HEI9/10 P6/7 Silicon T1 Td Tv2a V1/2/3 Vc Vsi antisite dangling-bond mono(=1) motional-effect n-type p-type pair(=2) quartet semi-insulating spin-relaxation triplet vacancy .inp files: SiC/Baranov/Baranov_g.inp SiC/EI5_C1h/5.inp SiC/EI5_C3v/5.inp SiC/EI6_RT/6.inp SiC/HEI10/HEI10a.inp SiC/HEI10/HEI10b.inp SiC/HEI1_C1h/1.inp SiC/HEI9/HEI9a.inp SiC/HEI9/HEI9b.inp SiC/SI5_C1h/4.inp SiC/Ky2/Ky2.inp SiC/Tv2a/Main.INP SiC/Vsi-_II_4H/Main.INP SiC/Vsi-_II_6H/Main.INP SiC/Vsi-_I_4H/Main.INP SiC/Vsi-_I_6H/Main.INP | last update: Takahide Umeda
- 6. Appl. Phys. Lett. 91, 133507 (2007) , “Identification of atomic-scale defect structure involved in the negative bias temperature instability in plasma-nitrided devices”, J. P. Campbell, P. M. Lenahan, A. T. Krishnan, and S. KrishnanWe utilize a very sensitive electron spin resonance technique called spin-dependent tunneling to identify defect centers involved in the negative bias temperature instability in plasma-nitrided p-channel metal-oxide-silicon field-effect transistors. The defect's 29Si hyperfine... (Read more)
- 7. Appl. Phys. Lett. 90, 123502 (2007) , “Observation of negative bias stressing interface trapping centers in metal gate hafnium oxide field effect transistors using spin dependent recombination”,The authors combine metal oxide semiconductor (MOS) gated diode measurements and very sensitive electrically detected electron spin resonance measurements to detect and identify negative bias temperature instability (NBTI) generated defect centers in fully processed HfO2 pMOS field effect... (Read more)
- 8. J. Appl. Phys. 102, 013530 (2007) , “Fluorine-vacancy complexes in Si-SiGe-Si structures”, D. A. Abdulmalik, P. G. Coleman, H. A. W. El Mubarek, and P. AshburnFluorine-vacancy (FV) complexes have been directly observed in the Si0.94Ge0.06 layer in a Si-SiGe-Si structure, using variable-energy positron annihilation spectroscopy (VEPAS). These complexes are linked to the significant reduction of boron diffusion in the SiGe layer via... (Read more)
- 9. J. Appl. Phys. 101, 013703 (2007) , “Electron spin resonance study of as-deposited and annealed (HfO2)x(SiO2)1−x high-κ dielectrics on Si”, B. B. Triplett, P. T. Chen, Y. Nishi, P. H. Kasai, J. J. Chambers, and L. ColomboElectron spin resonance measurements on 4 and 40 nm thick (HfO2)0.6(SiO2)0.4 and (HfO2)0.4(SiO2)0.6 high-κ films on (100)Si wafers detected Pb0 and Pb1... (Read more)
- 10. Phys. Rev. B 75, 245202 (2007) , “Identification of positively charged carbon antisite-vacancy pairs in 4H-SiC”, T. Umeda, J. Ishoya, T. Ohshima, N. Morishita, H. Itoh, and A. GaliAn antisite-vacancy pair and a monovacancy are a set of fundamental stable and/or metastable defects in compound semiconductors. Theory predicted that carbon antisite-vacancy pairs would be much more stable in p-type SiC than silicon vacancies and that they would be a common defect. However,... (Read more)
- 11. Phys. Rev. B 75, 195209 (2007) , “Mechanism and energetics of self-interstitial formation and diffusion in silicon”, Ramakrishnan Vaidyanathan, Michael Y. L. Jung, and Edmund G. SeebauerRecent work has suggested that prior determinations of diffusion mechanism and point defect thermodynamics in silicon have been affected by nonequilibrium effects stemming from uncontrolled adsorption-induced suppression of a pathway for defect creation at the surface. Through silicon self-diffusion... (Read more)
- 12. Phys. Rev. B 75, 085439 (2007) , “Real-space investigation of fast diffusion of hydrogen on Si(001) by a combination of nanosecond laser heating and STM”, C. H. Schwalb, M. Lawrenz, M. Dürr,, and U. HöferThe rearrangement of silicon dangling bonds induced by pulsed laser heating of monohydride-covered Si(001) surfaces has been studied by means of scanning tunneling microscopy (STM). The initial configurations, which were created by laser-induced thermal desorption, consist of isolated pairs of... (Read more)
- 13. Phys. Rev. B 75, 085208 (2007) , “Clustering of vacancy defects in high-purity semi-insulating SiC”, R. Aavikko, K. Saarinen, F. Tuomisto, B. Magnusson, N. T. Son, and E. JanzénPositron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the... (Read more)
- 14. Phys. Rev. B 75, 075306 (2007) , “Microcrack-induced strain relief in GaN/AlN quantum dots grown on Si(111)”, G. Sarusi, O. Moshe, S. Khatsevich, D. H. Rich, and B. DamilanoThe optical properties of vertically stacked self-assembled GaN/AlN quantum dots (QD's) grown on Si substrates were studied by means of temporally and spatially resolved cathodoluminescence (CL). An analysis of the CL spectra, thermal activation energies, and measured decay times of the QD... (Read more)
- 15. Phys. Rev. B 75, 075304 (2007) , “Damage evolution in low-energy ion implanted silicon”, R. Karmouch, Y. Anahory, J.-F. Mercure, D. Bouilly, M. Chicoine, G. Bentoumi, R. Leonelli, Y. Q. Wang, and F. SchiettekatteThe annealing of damage generated by low-energy ion implantation in polycrystalline silicon (poly-Si) and amorphous silicon (a-Si) is compared. The rate of heat release between implantation temperature and 350–500 °C for Si implanted in both materials and for different ions implanted in... (Read more)
- 16. Phys. Rev. B 75, 045210 (2007) , “Positron trapping kinetics in thermally generated vacancy donor complexes in highly As-doped silicon”, K. Kuitunen, K. Saarinen, and F. TuomistoWe have measured positron lifetime and Doppler broadening in highly As-doped silicon containing thermally generated V-As3 defect complexes (vacancy is surrounded by three arsenic atoms). We observe positron detrapping from the V-As3 defect complex and determine... (Read more)
- 17. Phys. Rev. B 75, 035309 (2007) , “Role of hydrogen in hydrogen-induced layer exfoliation of germanium”, J. M. Zahler, A. Fontcuberta i Morral, M. J. Griggs, Harry A. Atwater, and Y. J. ChabalThe role of hydrogen in the exfoliation of Ge is studied using cross-sectional transmission electron microscopy, atomic force microscopy, and multiple-internal transmission mode Fourier-transform infrared absorption spectroscopy and compared with the mechanism in silicon. A qualitative model for the... (Read more)
- 18. Phys. Rev. B 75, 035211 (2007) , “Self- and foreign-atom diffusion in semiconductor isotope heterostructures. II. Experimental results for silicon”, H. Bracht, H. H. Silvestri, I. D. Sharp, and E. E. HallerWe report the diffusion of boron, arsenic, and phosphorus in silicon isotope multilayer structures at temperatures between 850 °C and 1100 °C. The diffusion of all dopants and self-atoms at a given temperature is modeled with the same setting of all native-point-defect-related parameters.... (Read more)
- 19. Phys. Rev. Lett. 98, 216103 (2007) , “Influence of Cumulenic Chains on the Vibrational and Electronic Properties of sp-sp2 Amorphous Carbon”, L. Ravagnan, P. Piseri, M. Bruzzi, S. Miglio, G. Bongiorno, A. Baserga, C. S. Casari, A. Li Bassi, C. Lenardi, Y. Yamaguchi, T. Wakabayashi, C. E. Bottani, and P. MilaniWe report the production and characterization of a form of amorphous carbon with sp-sp2 hybridization (atomic fraction of sp hybridized species 20%) where the predominant sp bonding appears to be (=C=C=)n cumulene.... (Read more)
- 20. Phys. Rev. Lett. 98, 206406 (2007) , “Role of Intermolecular Coupling in the Photophysics of Disordered Organic Semiconductors: Aggregate Emission in Regioregular Polythiophene”, Jenny Clark, Carlos Silva, Richard H. Friend, and Frank C. SpanoWe address the role of excitonic coupling on the nature of photoexcitations in the conjugated polymer regioregular poly(3-hexylthiophene). By means of temperature-dependent absorption and photoluminescence spectroscopy, we show that optical emission is overwhelmingly dominated by weakly coupled H... (Read more)
- 21. Phys. Rev. Lett. 98, 095901 (2007) , “Experimental Evidence of the Vacancy-Mediated Silicon Self-Diffusion in Single-Crystalline Silicon”, Yasuo Shimizu, Masashi Uematsu, and Kohei M. ItohWe have determined silicon self-diffusivity at temperatures 735–875 °C based on the Raman shift of longitudinal optical phonon frequencies of diffusion annealed 28Si/30Si isotope superlattices. The activation enthalpy of 3.6 eV is obtained in such low temperature... (Read more)
- 22. Appl. Phys. Lett. 89, 191903 (2006) , “Vacancy self-trapping during rapid thermal annealing of silicon wafers”, Thomas A. Frewen and Talid SinnoThe density and spatial distribution of oxide precipitates within a crystalline silicon wafer is of paramount importance for microelectronic device yield. In this letter, the authors show how the formation of previously unconsidered, very small vacancy aggregates can explain macroscopic spatial... (Read more)
- 23. Appl. Phys. Lett. 89, 152123 (2006) , “Electrical characterization of defects introduced in n-type Ge during indium implantation”, F. D. Auret, P. J. Janse van Rensburg, M. Hayes, J. M. Nel, W. E. Meyer, S. Decoster, V. Matias, and A. VantommeThe authors have employed deep level transient spectroscopy to investigate the defects introduced in n-type Ge during 160 keV indium (In) ion implantation. Our results show that In implantation introduces three prominent electron traps with energy levels at... (Read more)
- 24. Appl. Phys. Lett. 89, 112121 (2006) , “Nature and stability of the (100)Si/LaAlO3 interface probed by paramagnetic defects”, A. Stesmans, K. Clémer, V. V. Afanas'ev, L. F. Edge, and D. G. SchlomElectron spin resonance analysis of (100)Si/LaAlO3 structures reveals the absence of a Si/SiO2-type interface in terms of archetypal Si-dangling bond-type Si/SiO2 interface defects (Pb0,Pb1). With no... (Read more)
- 25. Appl. Phys. Lett. 89, 092902 (2006) , “Charge trapping in nitrided HfSiO gate dielectric layers”, G. Vellianitis, Z. M. Rittersma, and J. PétryThe effects of HfSiO nitridation on charge trapping and long-term dielectric reliability are investigated. A comparison between decoupled plasma nitridation, annealing in NH3, and no nitridation is made. It was found that thinner HfSiO layers show less trapped charge. Decoupled plasma... (Read more)
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