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- 1. Appl. Phys. Express 3, 051002 (2010) , “Nitrogen Related Electron Trap with High Capture Cross Section in n-Type GaAsN Grown by Chemical Beam Epitaxy”, Boussairi Bouzazi, Hidetoshi Suzuki, Nobuaki Kojima, Yoshio Ohshita, and Masafumi YamaguchiA nitrogen-related electron trap, at around 0.3 eV from the conduction band minimum of n-type GaAsN grown by chemical beam epitaxy, is confirmed using deep level transient spectroscopy and nitrogen concentration dependence of its density. It has a high capture cross section and not observed in N... (Read more)
- 2. Appl. Phys. Express 3, 031103 (2010) , “High-Quality p-Type ZnO Films Grown by Co-Doping of N and Te on Zn-Face ZnO Substrates”, Seunghwan Park, Tsutomu Minegishi, Dongcheol Oh, Hyunjae Lee, Toshinori Taishi, Jinsub Park, Mina Jung, Jiho Chang, Inho Im, Junseok Ha, Soonku Hong, Ichiro Yonenaga, Toyohiro Chikyow, and Takafumi YaoThis article will report the epitaxial growth of high-quality p-type ZnO layers on Zn-face ZnO substrates by nitrogen and tellurium (N+Te) co-doping. ZnO:[N+Te] films show p-type conductivity with a hole concentration of 4×1016 cm-3, while ZnO:N shows n-type... (Read more)
- 3. Jpn. J. Appl. Phys. 49, 071302 (2010) , “Deep-Level Transient Spectroscopy and Photoluminescence Studies of Formation and Depth Profiles of Copper Centers in Silicon Crystals Diffused with Dilute Copper”, Minoru Nakamura and Susumu MurakamiWe have observed the formation of the Cu centers in p-type Si crystals diffused with dilute Cu between 400 and 1000 °C by deep-level transient spectroscopy (DLTS) and photoluminescence methods. For the samples diffused below 800 °C, a DLTS Cu center denoted as the CuDLB center was... (Read more)
- 4. Jpn. J. Appl. Phys. 49, 05FE02 (2010) , “Photoinduced Leakage Currents in Silicon Carbon Nitride Dielectrics for Copper Diffusion Barriers”, Kiyoteru Kobayashi and Taketoshi IdeThe current conduction in silicon carbon nitride (SiCN) dielectric films subjected to ultraviolet (UV) illumination at room temperature has been investigated. After exposure of SiCN single-layer and SiCN–SiO2 double-layer films to 4.9-eV UV illumination, leakage currents through... (Read more)
- 5. Jpn. J. Appl. Phys. 49, 051001 (2010) , “Nitrogen-Related Recombination Center in GaAsN Grown by Chemical Beam Epitaxy”, Boussairi Bouzazi, Hidetoshi Suzuki, Nobuaki Kojima, Yoshio Ohshita, and Masafumi YamaguchiA nitrogen-related deep electron trap, at approximately 0.33 eV below the conduction band minimum of GaAsN grown by chemical beam epitaxy, is confirmed to act as a recombination center. The level is found to be responsible for the reverse bias current in the depletion region of n-type GaAsN schottky... (Read more)
- 6. Appl. Phys. Express 2, 091101 (2009) , “Elimination of the Major Deep Levels in n- and p-Type 4H-SiC by Two-Step Thermal Treatment”, Toru Hiyoshi and Tsunenobu KimotoBy thermal oxidation of 4H-SiC at 1150–1300 °C, the Z1/2 and EH6/7 concentrations can be reduced to below 1×1011 cm-3. By the oxidation, however, a high concentration of HK0 center (EV + 0.78 eV) is generated.... (Read more)
- 7. Appl. Phys. Express 2, 041101 (2009) , “Reduction of Deep Levels and Improvement of Carrier Lifetime in n-Type 4H-SiC by Thermal Oxidation”, Toru Hiyoshi and Tsunenobu KimotoSignificant reduction of major deep levels in n-type 4H-SiC(0001) epilayers by means of thermal oxidation is demonstrated. By thermal oxidation of epilayers at 1150–1300 °C, the concentration of the Z1/2 and EH6/7 centers has been reduced from... (Read more)
- 8. Appl. Phys. Lett. 94, 092105 (2009) , “Interaction of oxygen with thermally induced vacancies in Czochralski silicon”, V. Akhmetov, G. Kissinger, and W. von AmmonComplexes consisting of a vacancy and four oxygen atoms, VO4, were found in oxygen-rich Czochralski silicon wafers subjected to rapid thermal annealing (RTA) at 1250 °C for 30 s in Ar/O2 atmosphere by means of Fourier transform infrared spectroscopy with enhanced... (Read more)
- 9. Appl. Phys. Lett. 94, 091903 (2009) , “Photoluminescence studies of impurity transitions in Mg-doped AlGaN alloys”, M. L. Nakarmi, N. Nepal, J. Y. Lin, and H. X. JiangDeep ultraviolet photoluminescence spectroscopy was employed to study the impurity transitions in Mg-doped AlGaN alloys. A group of deep level impurity transitions was observed in Mg-doped AlxGa1−xN alloys, which was identified to have the same origin as the... (Read more)
- 10. Appl. Phys. Lett. 94, 061910 (2009) , “Defect formation and annealing behaviors of fluorine-implanted GaN layers revealed by positron annihilation spectroscopy”, M. J. Wang, L. Yuan, C. C. Cheng, C. D. Beling, and K. J. ChenDefect formation and annealing behaviors of fluorine-implanted, unintentionally doped GaN layers were studied by positron annihilation spectroscopy (PAS). Single Ga vacancies (VGa) were identified as the main vacancy-type defects detected by PAS after fluorine implantation at 180... (Read more)
- 11. J. Appl. Phys. 105, 053709 (2009) , “Deep levels in GaTe and GaTe:In crystals investigated by deep-level transient spectroscopy and photoluminescence”, Yunlong Cui, David D. Caudel, Pijush Bhattacharya, Arnold Burger, Krishna C. Mandal, D. Johnstone, and S. A. PayneDeep levels of undoped GaTe and indium-doped GaTe crystals are reported for samples grown by the vertical Bridgman technique. Schottky diodes of GaTe and GaTe:In have been fabricated and characterized using current-voltage, capacitance-voltage, and deep-level transient spectroscopy (DLTS). Three... (Read more)
- 12. J. Appl. Phys. 105, 013504 (2009) , “Behaviors of neutral and charged silicon self-interstitials during transient enhanced diffusion in silicon investigated by isotope superlattices”, Yasuo Shimizu, Masashi Uematsu, Kohei M. Itoh, Akio Takano, Kentarou Sawano, and Yasuhiro ShirakiWe investigated the contributions of neutral and charged silicon self-interstitials to self- and boron diffusion during transient enhanced diffusion in silicon. We simultaneously observed self- and boron diffusion in silicon using natSi/28Si isotope superlattices. A calculation... (Read more)
- 13. Jpn. J. Appl. Phys. 48, 081003 (2009) , “Effects of Phosphorus Implantation on the Activation of Magnesium Doped in GaN”, Kuan-Ting Liu, Shoou-Jinn Chang, and Sean WuThe effects of phosphorus implantation on the activation of magnesium doped in GaN at different dopant concentration ratios have been systematically investigated. Hall effect measurements show that P implantation improves the hole concentration, and that this improvement is dependent on P/Mg dopant... (Read more)
- 14. Jpn. J. Appl. Phys. 48, 031205 (2009) , “Dual-Sublattice Modeling and Semi-Atomistic Simulation of Boron Diffusion in 4H-Silicon Carbide”, Kazuhiro Mochizuki, Haruka Shimizu, and Natsuki YokoyamaReported profiles of high-temperature (500 °C)-implanted boron ions diffused in 4H-silicon carbide at 1200–1900 °C for 5–90 min were simulated through a “dual-sublattice” modeling, in which a different diffusivity is assigned for diffusion via each sublattice, and a... (Read more)
- 15. Phys. Rev. B 79, 075207 (2009) , “EPR study of local symmetry sites of Ce3+ in Pb1−xCexA (A=S, Se, and Te)”, X. Gratens, V. Bindilatti, V. A. Chitta, N. F. Oliveira, and Jr.The local site symmetry of Ce3+ ions in the diluted magnetic semiconductors Pb1−xCexA (A=S, Se, and Te) has been investigated by electron-paramagnetic resonance (EPR). The experiments were carried out on single crystals with cerium... (Read more)
- 16. Phys. Rev. B 79, 075203 (2009) , “Hyperfine interaction in the ground state of the negatively charged nitrogen vacancy center in diamond”, S. Felton, A. M. Edmonds, and M. E. NewtonThe 14N, 15N, and 13C hyperfine interactions in the ground state of the negatively charged nitrogen vacancy (NV−) center have been investigated using electron-paramagnetic-resonance spectroscopy. The previously published parameters for the... (Read more)
- 17. Phys. Rev. B 79, 075201 (2009) , “First-principles studies of small arsenic interstitial complexes in crystalline silicon”, Yonghyun Kim, Taras A. Kirichenko, Ning Kong, Graeme Henkelman, and Sanjay K. BanerjeeWe present a first-principles study of the structure and dynamics of small As-interstitial complexes (AsI2, As2I2, AsI3, and As2I3) in crystalline Si. These complexes can be important components of stable As-interstitial clusters or... (Read more)
- 18. Phys. Rev. B 79, 014102 (2009) , “Vacancy defect positron lifetimes in strontium titanate”, R. A. Mackie, S. Singh, J. Laverock, S. B. Dugdale, and D. J. KeebleThe results of positron-annihilation lifetime spectroscopy measurements on undoped, electron-irradiated, and Nb-doped SrTiO3 single crystals are reported. Perfect lattice and vacancy defect positron lifetimes were calculated using two different first-principles schemes. The Sr-vacancy... (Read more)
- 19. Phys. Rev. Lett. 102, 075506 (2009) , “Proton Tunneling: A Decay Channel of the O-H Stretch Mode in KTaO3”, E. J. Spahr, L. Wen, M. Stavola, L. A. Boatner, L. C. Feldman, N. H. Tolk, and G. LüpkeThe vibrational lifetimes of the O-H and O-D stretch modes in the perovskite oxide KTaO3 are measured by pump-probe infrared spectroscopy. Both stretch modes are exceptionally long lived and exhibit a large “reverse” isotope effect, due to a phonon-assisted proton-tunneling process, which involves the O-Ta-O bending motion. The excited-state tunneling rate is found to be 7 orders of magnitude larger than from the ground state in the proton conducting oxide, BaCeO3 [Phys. Rev. B 60, R3713 (1999)]. (Read more)
- 20. Phys. Rev. Lett. 102, 065502 (2009) , “Transition Metal Impurities on the Bond-Centered Site in Germanium”, S. Decoster, S. Cottenier, B. De Vries, H. Emmerich, U. Wahl, J. G. Correia, and A. VantommeWe report on the lattice location of ion implanted Fe, Cu, and Ag impurities in germanium from a combined approach of emission channeling experiments and ab initio total energy calculations. Following common expectation, a fraction of these transition metals (TMs) was found on the... (Read more)
- 21. Angew. Chem. Int. Ed. 47, (2008) , Wily , “Ag@AgCl: A Highly Efficient and Stable Photocatalyst Active under Visible Light”, PengWang, Baibiao Huang,* Xiaoyan Qin, Xiaoyang Zhang, Ying Dai, JiyongWei, and Myung-Hwan Whangbo
- 22. Appl. Phys. Lett. 93, 152108 (2008) , “Internal gettering of iron in multicrystalline silicon at low temperature”, Rafael Krain, Sandra Herlufsen, and Jan SchmidtThe interstitial iron concentration in multicrystalline silicon wafers, determined from recombination lifetime measurements, is effectively reduced by annealing the wafers at very low temperature (300–500 °C). During annealing, the iron concentration decreases by more than one order of... (Read more)
- 23. Appl. Phys. Lett. 93, 141907 (2008) , “Experimental evidence of tetrahedral interstitial and bond-centered Er in Ge”, S. Decoster, B. De Vries, U. Wahl, J. G. Correia, and A. VantommeWe report on an emission channeling study of the lattice site location of implanted Er in Ge together with its thermal stability. We found direct experimental evidence of Er atoms located on the tetrahedral (T) interstitial site and on the bond-centered (BC) site, with a maximum total occupancy... (Read more)
- 24. Appl. Phys. Lett. 93, 113504 (2008) , “Voltage polarity dependent low-power and high-speed resistance switching in CoO resistance random access memory with Ta electrode”, Hisashi Shima, Fumiyoshi Takano, Hidenobu Muramatsu, Hiro Akinaga, Yukio Tamai, Isao H. Inque, and Hidenori Takagi,Structural and resistance switching properties were investigated in the CoO resistance random access memory (RRAM) with the Ta electrode. The intermediate layer consisting of Co and Ta oxides was confirmed at the interface by the transmission electron microscopy and electron energy loss... (Read more)
- 25. Appl. Phys. Lett. 93, 103505 (2008) , “Misfit point defects at the epitaxial Lu2O3/(111)Si interface revealed by electron spin resonance”, A. Stesmans, P. Somers, V. V. Afanas'ev, W. Tian, L. F. Edge, and D. G. SchlomElectron spin resonance study on heteroepitaxial Si/insulator structures obtained through the growth of epi-Lu2O3 films on (111)Si (~4.5 % mismatched) by reactive molecular beam epitaxy indicates the presence in the as-grown state of interfacial Pb... (Read more)
- 26. Appl. Phys. Lett. 93, 072102 (2008) , AIP , “Broadband electrically detected magnetic resonance of phosphorus donors in a silicon field-effect transistor”, L. H. Willems van Beveren, H. Huebl, D. R. McCamey, T. Duty, A. J. Ferguson, R. G. Clark, and M. S. BrandtWe report electrically detected magnetic resonance of phosphorus donors in a silicon field-effect transistor. An on-chip transmission line is used to generate the oscillating magnetic field allowing broadband operation. At millikelvin temperatures, continuous wave spectra were obtained up to 40 ... (Read more)
- 27. Appl. Phys. Lett. 93, 032108 (2008) , “High-temperature annealing behavior of deep levels in 1 MeV electron irradiated p-type 6H-SiC”, Giovanni Alfieri and Tsunenobu KimotoWe report on the thermal stability of deep levels detected after 1 MeV electron irradiated p-type 6H-SiC. The investigation was performed by deep level transient spectroscopy, and an isochronal annealing series was carried out in the 373–2073 K temperature range. We found seven... (Read more)
- 28. Appl. Phys. Lett. 92, 222109 (2008) , “Deep level defects in a nitrogen-implanted ZnO homogeneous p-n junction”, Q. L. Gu, C. C. Ling, G. Brauer, W. Anwand, W. Skorupa, Y. F. Hsu, A. B. Djurišić, C. Y. Zhu, S. Fung, and L. W. LuNitrogen ions were implanted into undoped melt grown ZnO single crystals. A light-emitting p-n junction was subsequently formed by postimplantation annealing in air. Deep level transient spectroscopy was used to investigate deep level defects induced by N+ implantation and... (Read more)
- 29. Appl. Phys. Lett. 92, 142105 (2008) , “Electric field assisted annealing and formation of prominent deep-level defect in ion-implanted n-type 4H-SiC”, J. Wong-Leung and B. G. SvenssonHigh-purity and low-doped n-type epitaxial layers of 4H-SiC have been implanted with N and C ions by using energies in the MeV range and doses from 2×108 to 1×109 cm−2. Postimplant annealing was performed at 1100 °C prior to... (Read more)
- 30. Appl. Phys. Lett. 92, 132104 (2008) , “Analysis of electronic memory traps in the oxide-nitride-oxide structure of a polysilicon-oxide-nitride-oxide-semiconductor flash memory”, Y. J. Seo, K. C. Kim, and T. G. KimThe origin of the electron memory trap in an oxide-nitride-oxide structure deposited on n-type Si is investigated by both capacitance-voltage and deep level transient spectroscopy (DLTS). Two electron traps are observed near 0.27 and 0.54 eV, below the conduction band minimum of Si and are... (Read more)
- 31. Appl. Phys. Lett. 92, 132102 (2008) , “On the identity of a crucial defect contributing to leakage current in silicon particle detectors”, J. H. Bleka, L. Murin, E. V. Monakhov, B. S. Avset, and B. G. SvenssonThe annealing kinetics of the so-called E4/E5 center or E4a/E4b center in electron-irradiated Si particle detectors has been studied at four different temperatures from 23 to 65 °C using deep-level transient spectroscopy (DLTS). The center gives rise to two energy levels at 0.37 and 0.45 eV... (Read more)
- 32. J. Appl. Phys. 104, 093711 (2008) , “Electrical properties of high energy ion irradiated 4H-SiC Schottky diodes”, G. Izzo, G. Litrico, L. Calcagno, G. Foti, and F. La ViaThe changes in the electrical properties of 4H-SiC epitaxial layer induced by irradiation with 7.0 MeV C+ ions were investigated by current-voltage measurements and deep level transient spectroscopy (DLTS). Current-voltage characteristics of the diodes fabricated from epilayers... (Read more)
- 33. J. Appl. Phys. 104, 093521 (2008) , “Native defects and oxygen and hydrogen-related defect complexes in CdTe: Density functional calculations”, Mao-Hua Du, Hiroyuki Takenaka, and David J. SinghWe study structural and electronic properties of various intrinsic and extrinsic defects in CdTe based on first-principles calculations. The focus is given to the role of these defects in the carrier compensation in semi-insulating CdTe, which is essential for the CdTe-based radiation detectors. The... (Read more)
- 34. J. Appl. Phys. 104, 083702 (2008) , “A bistable divacancylike defect in silicon damage cascades”, R. M. Fleming, C. H. Seager, D. V. Lang, E. Bielejec, and J. M. CampbellTwo deep level transient spectroscopy (DLTS) electron emission signatures, previously labeled E4 and E5, have been shown to be bistable with respect to minority carrier injection at room temperature. These result from two charge state transitions of the same defect. We have performed DLTS... (Read more)
- 35. J. Appl. Phys. 104, 054110 (2008) , “The effect of implanting boron on the optical absorption and electron paramagnetic resonance spectra of silica”, R. H. Magruder, III, A. Stesmans, R. A. Weeks,, and R. A. WellerSilica samples (type III, Corning 7940) were implanted with B using multiple energies to produce a layer ~600 nm thick in which the concentration of B ranged from 0.034 to 2.04 at. %. Optical absorption spectra were measured from 1.8 to 6.5 eV. Electron paramagnetic resonance (EPR) measurements... (Read more)
- 36. J. Appl. Phys. 104, 043702 (2008) , “Mechanisms of unexpected reduction in hole concentration in Al-doped 4H-SiC by 200 keV electron irradiation”, Hideharu Matsuura, Nobumasa Minohara, and Takeshi OhshimaThe hole concentration in Al-doped p-type 4H-SiC was found to be significantly reduced by electron irradiation when compared to the hole concentration in Al-doped p-type Si; this is an unexpected result. The temperature dependence of the hole concentration p(T) in... (Read more)
- 37. J. Appl. Phys. 104, 023705 (2008) , “Study of metal-related deep-level defects in germanide Schottky barriers on n-type germanium”, E. Simoen, K. Opsomer, C. Claeys, K. Maex, C. Detavernier, R. L. Van Meirhaeghe, and P. ClauwsDeep levels have been studied in n-type germanium subjected to Co, Fe, Cu, Cr, and Pt germanidation in the temperature range between 300 and 700 °C by deep-level transient spectroscopy (DLTS). It is shown that most DLTS peaks can be assigned to acceptor levels of substitutional metal... (Read more)
- 38. J. Appl. Phys. 104, 014106 (2008) , “Analysis of electrically biased paramagnetic defect centers in HfO2 and HfxSi1−xO2 / (100)Si interfaces”, P. T. Chen, B. B. Triplett, J. J. Chambers, L. Colombo, P. C. McIntyre, and Y. NishiThis study reports on the first experimental observations of electrically biased paramagnetic defects at 800 °C N2 annealed HfxSi1−xO2 (x=0.4, and 0.6)/(100)Si and HfO2/(100)Si interfaces in metal oxide silicon... (Read more)
- 39. J. Appl. Phys. 103, 123709 (2008) , “Optical detection of magnetic resonance and electron paramagnetic resonance study of the oxygen vacancy and lead donors in ZnO”, R. Laiho, L. S. Vlasenko, and M. P. VlasenkoOptical detection of magnetic resonance (ODMR) and electron paramagnetic resonance (EPR) spectra are investigated in ZnO single crystals. The strong negative ODMR line with axial symmetry of the g-tensor around the c axis with g=2.0133±0.0001 and... (Read more)
- 40. J. Appl. Phys. 103, 104505 (2008) , “Vacancy-type defects in Er-doped GaN studied by a monoenergetic positron beam”, A. Uedono, C. Shaoqiang, S. Jongwon, K. Ito, H. Nakamori, N. Honda, S. Tomita, K. Akimoto, H. Kudo, and S. IshibashiA relationship between intra-4f transitions of Er and vacancy-type defects in Er-doped GaN was studied by using a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured for Er-doped GaN grown by molecular beam epitaxy. A clear correlation between... (Read more)
- 41. J. Appl. Phys. 103, 094901 (2008) , “Investigation of the origin of deep levels in CdTe doped with Bi”, E. Saucedo, J. Franc, H. Elhadidy, P. Horodysky, C. M. Ruiz, V. Bermúdez, and N. V. SochinskiiCombining optical (low temperature photoluminescence), electrical (thermoelectric effect spectroscopy), and structural (synchrotron X-ray powder diffraction) methods, the defect structure of CdTe doped with Bi was studied in crystals with dopant concentration in the range of... (Read more)
- 42. J. Appl. Phys. 103, 093701 (2008) , “Characterization of plasma etching damage on p-type GaN using Schottky diodes”, M. Kato, K. Mikamo, M. Ichimura, M. Kanechika, O. Ishiguro, and T. KachiThe plasma etching damage in p-type GaN has been characterized. From current-voltage and capacitance-voltage characteristics of Schottky diodes, it was revealed that inductively coupled plasma (ICP) etching causes an increase in series resistance of the Schottky diodes and compensation of... (Read more)
- 43. J. Appl. Phys. 103, 073716 (2008) , “Deep level transient spectroscopy and capacitance-voltage study of dislocations and associated defects in SiGe/Si heterostructures”, Jinggang Lu, Yongkook Park, and George A. RozgonyiThree SiGe/Si heterostructures with different Ge contents have been examined by deep level transient spectroscopy (DLTS) and capacitance-voltage techniques. DLTS revealed a broad band of traps from 80 to 250 K in the as-grown samples. Arrhenius plots of a 25% SiGe sample revealed three trap... (Read more)
- 44. J. Appl. Phys. 103, 044505 (2008) , “Identification of the atomic-scale defects involved in the negative bias temperature instability in plasma-nitrided p-channel metal-oxide-silicon field-effect transistors”, J. P. Campbell, P. M. Lenahan, A. T. Krishnan, and S. KrishnanWe utilize a combination of DC gate-controlled diode recombination current measurements as well as two very sensitive electrically detected magnetic resonance techniques, spin-dependent recombination and spin-dependent tunneling, to identify atomic-scale defects involved in the negative bias... (Read more)
- 45. J. Appl. Phys. 103, 043710 (2008) , “Further characterization of oxygen vacancies and zinc vacancies in electron-irradiated ZnO”, S. M. Evans, N. C. Giles, L. E. Halliburton, and L. A. KappersElectron paramagnetic resonance (EPR) has been used to monitor oxygen vacancies and zinc vacancies in a ZnO crystal irradiated near room temperature with 1.5 MeV electrons. Out-of-phase detection at 30 K greatly enhances the EPR signals from these vacancies. Following the electron irradiation, but... (Read more)
- 46. J. Appl. Phys. 103, 033701 (2008) , “Electron capture and emission properties of interface states in thermally oxidized and NO-annealed SiO2/4H-SiC”, X. D. Chen, S. Dhar, T. Isaacs-Smith, J. R. Williams, L. C. Feldman, and P. M. MooneyPostoxidation annealing in nitric oxide (NO) results in a significant reduction of electronic states at SiO2/4H-SiC interfaces. Measurements of electron trapping dynamics at interface states in both thermally oxidized and NO annealed SiO2/4H-SiC interfaces were performed using... (Read more)
- 47. J. Appl. Phys. 103, 013710 (2008) , “Acceptor levels in GaSe:In crystals investigated by deep-level transient spectroscopy and photoluminescence”, Yunlong Cui, Ryan Dupere, and Arnold BurgerDeep-acceptor levels associated with indium in indium-doped GaSe crystals have been measured. High-quality Schottky diodes of GaSe:In have been fabricated and characterized using current-voltage, capacitance-voltage, and deep-level transient spectroscopy (DLTS). Four DLTS peaks at 127, 160, 248, and... (Read more)
- 48. 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)
- 49. Phys. Rev. B 78, 235204 (2008) , “Symmetry of the phosphorus donor in diamond from first principles”, Bozidar Butorac and Alison MainwoodPhosphorus is the only donor in diamond which can be used technologically. Several ab initio theoretical models have been published on substitutional phosphorus, and most of them have predicted that it should have tetrahedral or trigonal symmetry. Recent ab initio calculations... (Read more)
- 50. Phys. Rev. B 78, 235203 (2008) , “Electron paramagnetic resonance of sulfur at a split-vacancy site in diamond”, J. M. BakerIn natural diamonds a sulfur-related paramagnetic center labeled W31 has been previously tentatively assigned to an interstitial sulfur species in a positive charge state. However, we show by combining an assessment of available experimental data and density-functional simulations that the hyperfine... (Read more)
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