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- 1. Phys. Rev. B 75, 195215 (2007) , “Effect of Co and O defects on the magnetism in Co-doped ZnO: Experiment and theory”, G. S. Chang, E. Z. Kurmaev, D. W. Boukhvalov, L. D. Finkelstein, S. Colis, T. M. Pedersen, A. Moewes, and A. DiniaThe electronic structure of Zn1−xCoxO (x=0.02, 0.06, and 0.10) diluted magnetic semiconductors is investigated using soft x-ray emission spectroscopy and first-principles calculations. X-ray absorption and emission measurements reveal that most Co... (Read more)
- 2. Phys. Rev. B 75, 144404 (2007) , “Ferromagnetism in Fe-doped ZnO nanocrystals: Experiment and theory”, Debjani Karmakar, S. K. Mandal, R. M. Kadam, P. L. Paulose, A. K. Rajarajan, T. K. Nath, A. K. Das, I. Dasgupta, and G. P. DasFe-doped ZnO nanocrystals are successfully synthesized and structurally characterized by using x-ray diffraction and transmission electron microscopy. Magnetization measurements on the same system reveal a ferromagnetic to paramagnetic transition temperature above 450 K with a low-temperature... (Read more)
- 3. Phys. Rev. B 75, 144102 (2007) , “Theoretical investigation of nitrogen substitution in cubic zirconia”, Thomas BredowNitrogen substitution of oxygen ions in cubic zirconia was studied theoretically at density functional level. Nitrogen contents of 12.5 and 3.1% were studied with Zr8O16−mN2 and Zr32O64−mN2 supercells. For... (Read more)
- 4. Phys. Rev. B 75, 115206 (2007) , “Local-density-functional calculations of the vacancy-oxygen center in Ge”, A. Carvalho, R. Jones, J. Coutinho, V. J. B. Torres, S. Öberg, J. M. Campanera Alsina, M. Shaw, and P. R. BriddonWe carry out a comprehensive density-functional study of the vacancy-oxygen (VO) center in germanium using large H-terminated Ge clusters. The importance of a nonlinear core correction to account for the involvement of the 3d electrons in Ge-O bonds is discussed. We calculate the electrical... (Read more)
- 5. Phys. Rev. B 75, 075206 (2007) , “Isotope dependence of the vibrational lifetimes of light impurities in Si from first principles”, D. West and S. K. EstreicherThe vibrational lifetimes of a range of H-related defects and interstitial O (Oi) in Si, including isotopic substitutions, are calculated from first principles as a function of temperature. The theoretical approach is explained in detail. The vibrational lifetimes of... (Read more)
- 6. Phys. Rev. B 75, 075202 (2007) , “Theoretical study of Li and Na as n-type dopants for diamond”, J. P. Goss and P. R. BriddonPhosphorus is the n-type dopant of choice for diamond, but results in a deep donor level and alternatives are being sought. One possibility is the incorporation of interstitial alkali metal impurities such as Li and Na. We present the results of density-functional calculations used to predict... (Read more)
- 7. Phys. Rev. B 75, 024205 (2007) , “Mechanical strength and coordination defects in compressed silica glass: Molecular dynamics simulations”, Yunfeng Liang, Caetano R. Miranda, and Sandro ScandoloContrary to ordinary solids, which are normally known to harden by compression, the compressibility of SiO2 (silica) glass has a maximum at about 2–4 GPa and its mechanical strength shows a minimum around 10 GPa. At this pressure, the compression of silica glass undergoes a change... (Read more)
- 8. Phys. Rev. B 75, 024109 (2007) , “Optical and EPR properties of point defects at a crystalline silica surface: Ab initio embedded-cluster calculations”, L. Giordano, P. V. Sushko, G. Pacchioni, and A. L. ShlugerWe have studied the structure and spectroscopic properties of the paramagnetic nonbridging oxygen hole center and of the Egamma[prime]" align="middle"> center at the hydroxylated silica surfaces using density functional theory and an embedded-cluster model. To investigate the... (Read more)
- 9. Phys. Rev. B 75, 014102 (2007) , “First-principles study of vacancy formation in hydroxyapatite”, Katsuyuki Matsunaga and Akihide KuwabaraFirst-principles plane-wave calculations were performed for hydroxyapatite (HAp) in order to investigate the electronic structure and vacancy formation mechanisms. The HAp unit cell contains PO4 tetrahedra and OH groups formed by covalent P-O and H-O bonds. Ca ions play a role for... (Read more)
- 10. Phys. Rev. Lett. 98, 196802 (2007) , “Origin of Charge Density at LaAlO3 on SrTiO3 Heterointerfaces: Possibility of Intrinsic Doping”, Wolter Siemons, Gertjan Koster, Hideki Yamamoto, Walter A. Harrison, Gerald Lucovsky, Theodore H. Geballe, Dave H. A. Blank, and Malcolm R. BeasleyAs discovered by Ohtomo and Hwang, a large sheet charge density with high mobility exists at the interface between SrTiO3 and LaAlO3. Based on transport, spectroscopic, and oxygen-annealing experiments, we conclude that extrinsic defects in the form of oxygen vacancies... (Read more)
- 11. Phys. Rev. Lett. 98, 196101 (2007) , “Oxygen Vacancies in High Dielectric Constant Oxide-Semiconductor Films”, Supratik Guha and Vijay NarayananWe provide evidence that the oxygen vacancy is a dominant intrinsic electronic defect in nanometer scaled hafnium oxide dielectric films on silicon, relevant to microelectronics technology. We demonstrate this by developing a general model for the kinetics of oxygen vacancy formation in... (Read more)
- 12. Phys. Rev. Lett. 98, 137202 (2007) , “Magnetizing Oxides by Substituting Nitrogen for Oxygen”, I. S. Elfimov, A. Rusydi, S. I. Csiszar, Z. Hu, H. H. Hsieh, H.-J. Lin, C. T. Chen, R. Liang, and G. A. SawatzkyWe describe a possible pathway to new magnetic materials with no conventional magnetic elements present. The substitution of nitrogen for oxygen in simple nonmagnetic oxides leads to holes in N 2p states which form local magnetic moments. Because of the very large Hund's rule coupling of... (Read more)
- 13. Phys. Rev. Lett. 98, 115503 (2007) , “Oxygen Vacancy Clustering and Electron Localization in Oxygen-Deficient SrTiO3: LDA+U Study”, Do Duc Cuong, Bora Lee, Kyeong Mi Choi, Hyo-Shin Ahn, Seungwu Han, and Jaichan LeeWe find, using a local density approximation +Hubbard U method, that oxygen vacancies tend to cluster in a linear way in SrTiO3, a prototypical perovskite oxide, accompanied by strong electron localization at the 3d state of the nearby Ti transition metal ion. The vacancy... (Read more)
- 14. Phys. Rev. Lett. 98, 045501 (2007) , “Dopability, Intrinsic Conductivity, and Nonstoichiometry of Transparent Conducting Oxides”, Stephan Lany and Alex ZungerExisting defect models for In2O3 and ZnO are inconclusive about the origin of conductivity, nonstoichiometry, and coloration. We apply systematic corrections to first-principles calculated formation energies ΔH, and validate our theoretical defect model against... (Read more)
- 15. Appl. Phys. Lett. 89, 262904 (2006) , “Oxygen vacancy in monoclinic HfO2: A consistent interpretation of trap assisted conduction, direct electron injection, and optical absorption experiments”, Peter Broqvist and Alfredo PasquarelloThe authors calculate energy levels associated with the oxygen vacancy in monoclinic HfO2 using a hybrid density functional which accurately reproduces the experimental band gap. The most stable charge states are obtained for varying Fermi level in the HfO2 band gap. To compare... (Read more)
- 16. Appl. Phys. Lett. 89, 202904 (2006) , “Effects of O vacancies and C doping on dielectric properties of ZrO2: A first-principles study”, Gargi Dutta, K. P. S. S. Hembram, G. Mohan Rao, and Umesh V. WaghmareThe authors determine electronic properties, structural stability, and dielectric response of zirconia (ZrO2) with oxygen vacancies (O vacancies) and carbon doping (C doping) using first-principles density functional theory calculations based on pseudopotentials and a plane wave basis.... (Read more)
- 17. Appl. Phys. Lett. 89, 152904 (2006) , “First principles calculations of oxygen vacancy passivation by fluorine in hafnium oxide”, Wei Chen, Qing-Qing Sun, Shi-Jin Ding, David Wei Zhang, and Li-Kang WangThe fluorine incorporation into HfO2 with oxygen vacancies has been investigated using first principles calculations. The authors show that atomic fluorine can efficiently passivate the neutral oxygen vacancy with excess energies of 4.98 and 4.39 eV for threefold- and... (Read more)
- 18. Appl. Phys. Lett. 89, 142914 (2006) , “Defect passivation in HfO2 gate oxide by fluorine”, K. Tse and J. RobertsonThe authors have calculated that fluorine substituting for oxygen gives no gap states in HfO2. This accounts for the good passivation of oxygen vacancies by F seen experimentally. Bonding arguments are used to account for why F may be the most effective passivant in ionic oxides such as... (Read more)
- 19. Appl. Phys. Lett. 89, 082908 (2006) , “Negative oxygen vacancies in HfO2 as charge traps in high-k stacks”, J. L. Gavartin, D. Muñoz Ramo, A. L. Shluger, G. Bersuker, and B. H. LeeThe optical excitation and thermal ionization energies of oxygen vacancies in m-HfO2 are calculated using a non-local density functional theory with atomic basis sets and periodic supercell. The thermal ionization energies of negatively charged V and... (Read more)
- 20. Appl. Phys. Lett. 88, 253504 (2006) , “Single silicon vacancy-oxygen complex defect and variable retention time phenomenon in dynamic random access memories”, T. Umeda, K. Okonogi, K. Ohyu, S. Tsukada, K. Hamada, S. Fujieda, and Y. MochizukiThe variable retention time phenomenon has recently been highlighted as an important issue in dynamic random access memory (DRAM) technology. Based on electrically detected magnetic resonance and simulation studies, we suggest that a single Si vacancy-oxygen complex defect is responsible for this... (Read more)
- 21. Appl. Phys. Lett. 88, 182903 (2006) , “Effects of Al addition on the native defects in hafnia”, Q. Li, K. M. Koo, W. M. Lau, P. F. Lee, J. Y. Dai, Z. F. Hou, X. G. GongTwo occupied native defect bands are experimentally detected in pure HfO2. The density of states of band one in the middle of the band gap reduces drastically with the Al addition, while that of band two slightly above the valence-band maximum remains rather unaffected. We attribute the... (Read more)
- 22. Appl. Phys. Lett. 88, 162107 (2006) , “Physical origin of threshold voltage problems in polycrystalline silicon/HfO2 gate stacks”, Dae Yeon Kim, Joongoo Kang, and K. J. ChangBased on theoretical calculations, we find that at p+ polycrystalline silicon (poly-Si)/HfO2 gates, Si interstitials are easily migrated from the electrode, forming HfSi bonds with a charge transfer to the electrode, and the resulting interface dipole raises the Fermi level... (Read more)
- 23. Appl. Phys. Lett. 88, 012101 (2006) , “The structure of the SiO2/Si(100) interface from a restraint-free search using computer simulations”, Dominik Fischer, Alessandro Curioni, Salomon Billeter, and Wanda AndreoniThe structure of the interface between SiO2 and Si(100) is investigated using the replica-exchange method driven by classical molecular dynamics simulations based on ab initio-derived interatomic potentials. Abrupt interfaces are shown to be unstable, whereas a substoichiometric... (Read more)
- 24. J. Appl. Phys. 99, 044105 (2006) , “Passivation of oxygen vacancy states in HfO2 by nitrogen”, K. Xiong, J. Robertson, and S. J. ClarkNitrogen is known to reduce leakage currents and charge trapping in high-dielectric-constant gate oxides such as HfO2. We show that this occurs because nitrogen, substituting for oxygen atoms next to oxygen vacancy sites, repels the occupied gap states due to the neutral and positively... (Read more)
- 25. Phys. Rev. B 74, 235207 (2006) , “Vacancy-enhanced ferromagnetism in Fe-doped rutile TiO2”, Jun Chen, Paul Rulis, Lizhi Ouyang, S. Satpathy, and W. Y. ChingBased on a series of supercell density functional calculations of Fe-doped TiO2 both with and without O vacancy (VO), we show that VO plays an important role in determining the magnetic properties of the dilute magnetic semiconductors (DMS). Without... (Read more)
- 26. Phys. Rev. B 74, 233201 (2006) , “Electronic and magnetic properties of V-doped anatase TiO2 from first principles”, Xiaosong Du, Qunxiang Li, Haibin Su, and Jinlong YangWe report a first-principles study on the geometric, electronic, and magnetic properties of V-doped anatase TiO2. The DFT+U (Hubbard coefficient) approach predicts semiconductor band structures for Ti1−xVxO2 (x=6.25% and... (Read more)
- 27. Phys. Rev. B 74, 184117 (2006) , “Ab initio thermodynamic properties of point defects and O-vacancy diffusion in Mg spinels”, Zbigniew odziana and Jacek PiechotaWe report ab initio plane wave density functional theory studies of thermodynamic properties of isolated cation substitutions and oxygen vacancies in magnesium spinel, MgAl2O4. The formation enthalpy of Ca, Cu, and Zn substitutions of Mg cation indicate that transition... (Read more)
- 28. Phys. Rev. B 74, 174407 (2006) , “Superexchange in dilute magnetic dielectrics: Application to (Ti,Co)O2”, K. Kikoin and V. FleurovWe extend the model of ferromagnetic superexchange in dilute magnetic semiconductors to the ferromagnetically ordered highly insulating compounds (dilute magnetic dielectrics). The intrinsic ferromagnetism without free carriers is observed in oxygen-deficient films of anatase TiO2 doped... (Read more)
- 29. Phys. Rev. B 74, 155208 (2006) , “Vibrational spectra of vitreous germania from first-principles”, Luigi Giacomazzi, P. Umari, and Alfredo PasquarelloWe report on a first-principles investigation of the structural and vibrational properties of vitreous germania (v-GeO2). Our work focuses on a periodic model structure of 168 atoms, but three smaller models are also studied for comparison. We first carry out a detailed structural... (Read more)
- 30. Phys. Rev. B 74, 153403 (2006) , “Doping and the unique role of vacancies in promoting the magnetic ground state in carbon nanotubes and C60 polymers”, Antonis N. Andriotis, R. Michael Sheetz, and Madhu MenonThe role of various types of defects in establishing the magnetic properties of the C60-based polymers and the single-wall carbon nanotubes is investigated. Comparing the role of carbon vacancies, and that of substitutional impurity atoms X (X=N, B, O, Si, P, and S) in... (Read more)
- 31. Phys. Rev. B 74, 125203 (2006) , “Density functional theory of structural transformations of oxygen-deficient centers in amorphous silica during hole trapping: Structure and formation mechanism of the Egamma[prime]" align="middle"> center”, T. Uchino and T. YokoWe investigate the hole trapping process of a neutral oxygen vacancy in amorphous silicon dioxide (a-SiO2) using cluster calculations based on the density functional theory (DFT) method. We show that trapping a hole at a neutral oxygen vacancy leads to the formation of several... (Read more)
- 32. Phys. Rev. B 73, 245210 (2006) , “First-principles investigation of a bistable boron-oxygen interstitial pair in Si”, A. Carvalho, R. Jones, M. Sanati, S. K. Estreicher, J. Coutinho, and P. R. BriddonLocal density functional calculations are used to predict and compare the properties of the two distinct interstitial boron-interstitial oxygen (BiOi) complexes recently reported in the literature. The electronic and free energies, as well as the small... (Read more)
- 33. Phys. Rev. B 73, 235211 (2006) , “Ab initio calculations for the interconversion of optically active defects in amorphous silica”, M. M. G. Alemany and James R. ChelikowskyUsing ab initio calculations on clusters, we have identified a new reaction path between the dicoordinated silicon atom defect and the paramagnetic Egamma[prime]" align="middle"> center in amorphous silica. Under ionizing irradiation, the dicoordinated silicon atom... (Read more)
- 34. Phys. Rev. B 73, 235209 (2006) , “Temperature dependence of the vibrational spectrum of a Li-OH complex in ZnO: Infrared absorption experiments and theory”, Kevin R. Martin, Philip Blaney, Gang Shi, Michael Stavola, and W. Beall FowlerConsiderable interest has developed in the potential use of IIVI oxides as electronic and optical materials. In several cases, alkali atoms have been suggested as dopants. We report on the theoretical and experimental investigation of infrared and vibrational properties of a Li-OH complex in... (Read more)
- 35. Phys. Rev. B 73, 235206 (2006) , “LSDA+U study of cupric oxide: Electronic structure and native point defects”, Dangxin Wu and Qiming ZhangA first-principles study on strongly correlated monoclinic cupric oxide CuO has been performed by using the LSDA+U method. The optimized structural parameters of the crystal CuO are in good agreement with the experimental data. The electronic structures and magnetic properties calculated from the... (Read more)
- 36. Phys. Rev. B 73, 193202 (2006) , “First-principles study of point defects in rutile TiO2–x”, Eunae Cho, Seungwu Han, Hyo-Shin Ahn, Kwang-Ryeol Lee, Seong Keun Kim, and Cheol Seong HwangWe report our first-principles results on point defects in TiO2 in the rutile phase. Both the oxygen vacancy and titanium interstitial are considered. The size effect of the supercell has been examined and the localized state associated with the oxygen vacancy turns out to be sensitive to... (Read more)
- 37. Phys. Rev. B 73, 184105 (2006) , “Iron-oxygen vacancy defect association in polycrystalline iron-modified PbZrO3 antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis”, Hrvoje Metri, Rüdiger-A. Eichel, Klaus-Peter Dinse, Andrew Ozarowski, Johan van Tol, Louis Claude Brunel, Hans Kungl, Michael J. Hoffmann, Kristin A. Schönau, Michael Knapp, and Hartmut FuessBy utilizing multifrequency electron paramagnetic resonance (EPR) spectroscopy, the iron functional center in Fe3+-modified polycrystalline lead zirconate (PbZrO3) was studied. The single phase polycrystalline sample remained orthorhombic and antiferroelectric down to 20 K as... (Read more)
- 38. Phys. Rev. B 73, 115207 (2006) , “First-principles study of migration mechanisms and diffusion of oxygen in zinc oxide”, Paul Erhart and Karsten AlbeWe have performed density-functional theory calculations in conjunction with the climbing image nudged elastic band method in order to study the self-diffusion of oxygen in zinc oxide. To this end, we have derived the complete set of migration paths for vacancies as well as interstitials in wurtzite... (Read more)
- 39. Phys. Rev. Lett. 97, 256602 (2006) , “Bistability-Mediated Carrier Recombination at Light-Induced Boron-Oxygen Complexes in Silicon”, Mao-Hua Du, Howard M. Branz, Richard S. Crandall, and S. B. ZhangA first-principles study of the BO2 complex in B-doped Czochralski Si reveals a defect-bistability-mediated carrier recombination mechanism, which contrasts with the standard fixed-level Shockley-Read-Hall model of recombination. An O2 dimer distant from B causes only weak... (Read more)
- 40. Phys. Rev. Lett. 97, 116101 (2006) , “Oxygen Migration, Agglomeration, and Trapping: Key Factors for the Morphology of the Si-SiO2 Interface”, L. Tsetseris and S. T. PantelidesThe measured activation energies for oxide growth rates at the initial and late stages of oxidation of Si are 2 and 1.2 eV, respectively. These values imply that oxidation can proceed at temperatures much smaller than the 800 °C normally used to obtain devices with exceptionally smooth... (Read more)
- 41. Phys. Rev. Lett. 97, 066101 (2006) , “Structure and Interconversion of Oxygen-Vacancy-Related Defects on Amorphous Silica”, Chin-Lung Kuo and Gyeong S. HwangAtomic structure and structural stability of neutral oxygen vacancies on amorphous silica are investigated using combined Monte Carlo and density functional calculations. We find that, unlike their bulk counterparts, the Si-Si dimer configuration of surface oxygen vacancies is likely to be unstable... (Read more)
- 42. Appl. Phys. Lett. 87, 062105 (2005) , “Negative-U property of oxygen vacancy in cubic HfO2”, Y. P. Feng, A. T. L. Lim, M. F. LiOxygen vacancy in cubic HfO2 was investigated using first-principles calculation based on density functional theory and generalized gradient approximation. Five different charge states (V++, V+, V0, V, and... (Read more)
- 43. Appl. Phys. Lett. 86, 143507 (2005) , “First-principles studies of the intrinsic effect of nitrogen atoms on reduction in gate leakage current through Hf-based high-k dielectrics”, N. Umezawa, K. Shiraishi, T. Ohno, H. Watanabe, T. Chikyow, K. Torii, K. Yamabe, K. Yamada, H. Kitajima, T. ArikadoThe atomistic effects of N atoms on the leakage current through HfO2 high-k gate dielectrics have been studied from first-principles calculations within the framework of a generalized gradient approximation (GGA). It has been found that the intrinsic effects of N atoms drastically... (Read more)
- 44. J. Appl. Phys. 97, 053704 (2005) , “The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies”, J. L. Gavartin, A. L. Shluger, A. S. Foster, G. I. BersukerUsing ab initio density-functional total energy and molecular-dynamics simulations, we study the effects of various forms of nitrogen postdeposition anneal (PDA) on the electric properties of hafnia in the context of its application as a gate dielectric in field-effect transistors. We... (Read more)
- 45. Phys. Rev. B 71, 245203 (2005) , “Electrical Activity of Er and Er-O Centers in Silicon”, D. Prezzi, T. A. G. Eberlein, R. Jones, J. S. Filhol, J. Coutindo, M. J. Shaw, P. R. Briddon.Spin-polarized density functional calculations are carried out on Er and Er-oxygen defects in crystalline Si. We find that the interstitial site is favored but the diffusion barrier of Eri is only 1.9 eV, and inevitably Eri forms complexes with impurities and... (Read more)
- 46. Phys .Rev. Lett. 92, 178302 (2004) , “Nonvolatile Memory with Multilevel Switching: A Basic Model”, M. J. Rozenberg, I. H. Inoue, and M. J. SánchezThere is a current upsurge in research on nonvolatile two-terminal resistance random access memory (RRAM) for next generation electronic applications. The RRAM is composed of a simple sandwich of a semiconductor with two metal electrodes. We introduce here an initial model for RRAM with the... (Read more)
- 47. Phys. Rev. Lett. 93, 086102 (2004) , “Reaction of the Oxygen Molecule at the Si(100)–SiO2 Interface During Silicon Oxidation”, Angelo Bongiorno and Alfredo PasquarelloUsing constrained ab initio molecular dynamics, we investigate the reaction of the O2 molecule at the Si(100)SiO2 interface during Si oxidation. The reaction proceeds sequentially through the incorporation of the O2 molecule in a Si-Si bond and the... (Read more)
- 48. J. Appl. Phys. 94, 1 (2003) , “Negative bias temperature instability: Road to cross in deep submicron silicon semiconductor manufacturing”,We present an overview of negative bias temperature instability (NBTI) commonly observed in p-channel metaloxidesemiconductor field-effect transistors when stressed with negative gate voltages at elevated temperatures. We discuss the results of such stress on device and circuit... (Read more)
- 49. Appl. Phys. Lett. 81, 1818 (2002) , “Interface structures generated by negative-bias temperature instability in Si/SiO2 and Si/SiOxNy interfaces”, J. Ushio, T. Maruizumi, K. Kushida-AbdelghafarWe used a density functional method to investigate the mechanism of negative-bias temperature instability (NBTI) and resultant structural changes of Si/SiO2 and Si/SiOxNy interfaces. The reaction energies for the water- and hydrogen-originated... (Read more)
- 50. Appl. Phys. Lett. 78, 1571 (2001) , “Hydrogen Passivation and Activation of Oxygen Complexes in Silicon”, S. N. Rashkeev, M. Di Ventra, and S. T. PantelidesWe report first-principles calculations in terms of which we describe the role of hydrogen in passivating or activating oxygen complexes in Si. In particular we find that attaching H to a pre-existing oxygen cluster can change the electric activity of the cluster. Furthermore, the addition of a... (Read more)
- 51. J. Appl. Phys. 89, 5997-6001 (2001) , “Oxygen Recoil Implant from SiO2 Layers into Single-Crystalline Silicon”, G. Wang, Y. Chen, D. Li, S. Oak, G. Srivastav, S. Banerjee, A. Tasch, P. Merrill, R. Bleiler.It is important to understand the distribution of recoil-implanted atoms and the impact on device performance when ion implantation is performed at a high dose through surface materials into single crystalline silicon. For example, in ultralarge scale integration impurity ions are often implanted... (Read more)
- 52. Phys. Rev. Lett. 87, 235501 (2001) , “Thermal Double Donors and Quantum Dots”, J. Coutinho, R. Jones, L. I. Murin, V. P. Markevich, J. L. Lindstr?m, S. ?berg, P. R. Briddon.Combined local mode spectroscopy and ab initio modeling are used to demonstrate for the first time that oxygen atoms in thermal double donors (TDD) in Si are in close proximity. The observed vibrational modes in 16O, 18O, and mixed isotopic samples are consistent with a model... (Read more)
- 53. Phys. Rev. Lett. 86, 5522-5525 (2001) , “E' Centers in Amorphous SiO2 Revisited: A New Look at an Old Problem”, T. Uchino, M. Takahashi, T. YokoWe present theoretical evidence that the paramagnetic E? defect centers in amorphous silicon dioxide ( a-SiO2) do not have the same microscopic structures as those well-defined in the corresponding crystalline counterparts such as ?-quartz. We then present alternative models of... (Read more)
- 54. Phys. Rev. Lett. 86, 4560-4563 (2001) , “Structure and Generation Mechanism of the Peroxy-Radiacal Defect in Amorphous Silica”, T. Uchino, M. Takahashi, and T. YokoWe provide a new model of the peroxy-radical defect in amorphous silica on the basis of quantum-chemical calculations applied to clusters of atoms to model the defect. In this model, the 29Si hyperfine splittings of the peroxy radical arise from a single silicon, in agreement with the... (Read more)
- 55. Phys. Rev. Lett. 83, 372 (1999) , “Hydrogen Electrochemistry and Stress-Induced Leakage Current in Silica”, Peter E. Bl?chl and James H. StathisHydrogen-related defects in oxygen-deficient silica, representing the material of a thermal gate oxide, are analyzed using first-principles calculations. Energetics and charge-state levels of oxygen vacancies, hydrogen, and their complexes in the silica framework are mapped out. The neutral hydrogen... (Read more)
- 56. Nature 396, 58-60 (1998) , “Interface structure between silicon and its oxide by first-principles molecular dynamics”, A. Pasquarello, M. S. Hybertsen, R. CarThe requirement for increasingly thin (<50 Ã…) insulating oxide layers in silicon-based electronic devices highlights the importance of characterizing the Si–SiO2 interface structure at the atomic scale. Such a characterization relies to a large extent on an understanding of the atomic-scale mechanisms that govern the oxidation process. The widely used Deal–Grove model invokes a two-step process in which oxygen first diffuses through the amorphous oxide network before attacking the silicon substrate, resulting in the formation of new oxide at the buried interface1. But it remains unclear how such a process can yield the observed near-perfect interface2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Here we use first-principles molecular dynamics13, 14, 15 to generate a model interface structure by simulating the oxidation of three silicon layers. The resulting structure reveals an unexpected excess of silicon atoms at the interface, yet shows no bonding defects. Changes in the bonding network near the interface occur during the simulation via transient exchange events wherein oxygen atoms are momentarily bonded to three silicon atoms — this mechanism enables the interface to evolve without leaving dangling bonds. (Read more)
- 57. Phys. Rev. B 38, 9674-9685 (1988) , “Hyperfine interactions in cluster models of the Pb defect center”, M. Cook, C. T. WhiteHyperfine interactions in the Pb center (denoted schematically as Si3?Si?) at the Si(111)/SiO2 interface have been studied with use of spin-polarized self-consistent multiple-scattering X? calculations on Si22H21/Si6O18... (Read more)
- 58. J. Appl. Phys. 59, 3255-3266 (1986) , “Thermodynamic and Kinetic Considerations on the Equilibrium Shape for Thermally Induced Microdefects in Czochralski Silicon”, W. A. Tiller, S. Hahn, F. A. Ponce.Using thermodynamic and kinetic considerations, we explain the quasiequilibrium, morphological, and structural characteristics of thermally induced oxide precipitates in Czochralski silicon. A model based upon the formation of Frenkel defects at the silicon/silica interface is used to explain the... (Read more)
- 59. J. Appl. Phys. 54, 179-183 (1983) , “The Mechanism of the Enhancement of Divacancy Production by Oxygen During Electron Irradiation of Silicon. II. Computer Modeling”, G. S. Oehrlein, I. Krafcsik, J. L. Lindström, A. E. Jaworowski, and J. W. CorbettNumerical tests of possible models for the oxygen dependence of the divacancy introduction rate in silicon electron irradiated at room temperature were performed on a computer. Only the model in which oxygen traps Si self-interstitials can reproduce all the experimental data. Our modeling results... (Read more)
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