eV For Oxide Research Articles

Effect of Sodium Oxide and Sodium Fluoride in Gadolinium Phosphate Glasses Doped with Eu2O3 Content

Sodium gadolinium phosphate oxide and sodium gadolinium oxyfluoride glasses doped with europium oxide were prepared by melt-quenching technique. The physical, optical properties of the glass samples were studied. The density, molar volume and refractive index of the glass samples were carried out. Density and molar volume of oxide glass is more than oxyfluoride glass. The average phosphate to phosphate distance for oxide glass seems to be more than oxyfluoride glass. Polaron radius, inter-ionic radius shows 1.181 nm, 2.88 nm and 1.174 nm, 2.86 nm for oxide glass and oxyfluoride glasses respectively. Oxide electronic Polarizability and optical basicity of the oxide glass are lower than oxy-fluoride glass. Theoretical optical basicity shows higher for oxide glass than oxyfluoride suggesting increase in covalency of the cation to oxygen bonds in oxide glass. Optical band gap were estimated and found to be 3.061eV and 3.204 eV for oxide and oxyfluoride glass. Theoretical two photon absorption coefficient β were evaluated and found to be 11.96 and 10.80 for oxide and oxyfluoride glasses respectively. Furthermore, the glasses were subjected to study for their luminescence properties of the oxide and oxyfluoride glass samples.

Effect of sodium oxide and sodium fluoride in gadolinium phosphate glasses doped with Eu2O3 content

Sodium gadolinium phosphate oxide and sodium gadolinium oxyfluoride glasses doped with europium oxide were synthesized by melt-quenching method. The density, molar volume and refractive index of the glass samples were carried out. Density and molar volume of oxide glass is more than oxyfluoride glass. The average phosphate to phosphate distance for oxide glass seems to be more than oxyfluoride glass. Polaron radius, inter-ionic radius shows 1.181 nm, 2.88 nm and 1.174 nm, 2.86 nm for oxide glass and oxyfluoride glasses respectively. Oxide electronic Polarizability and optical basicity of the oxide glass are lower than oxy-fluoride glass. Theoretical optical basicity shows higher for oxide glass than oxyfluoride suggesting increase in covalency of the cation to oxygen bonds in oxide glass. Optical band gap was estimated and found to be 3.061eV and 3.204 eV for oxide and oxyfluoride glass. Theoretical two photon absorption coefficient β were evaluated and found to be 11.96 and 10.80 for oxide and oxyfluoride glasses respectively. Electron-phonon coupling strength were evaluated from the phonon side band spectra for the oxide and oxy-fluoride glasses. The asymmetry ratio (R) show higher for NaF doped glass than Na2O confirming their role in elevated ionicity for oxyfluoride glass than oxide glass. Furthermore, the glasses were subjected to study for their luminescence properties of the oxide and oxyfluoride glass samples.

Reorganization Free Energies for Long-Range Electron Transfer in a Porphyrin-Binding Four-Helix Bundle Protein

To explore the possibility of electron transport in a recently designed four-helix bundle protein (Cochran, F. V.; et al. J. Am. Chem. Soc. 2005, 127, 1346), we have computed the reorganization free energy for (i) oxidation of a single Ru-porphyrin cofactor and (ii) electron self-exchange between two Ru-porphyrin cofactors binding to the solvated protein. Sampling the classical electrostatic energy gap for 20 ns, we find that the fluctuations are well described by Gaussian statistics and obtain reorganization free energies of 0.90 +/- 0.04 eV for oxidation and 1.36 +/- 0.08 eV for self-exchange. The latter is 0.1-0.2 eV higher than the experimental estimate for interprotein electron self-exchange in cytochrome b5. As in natural electron carriers, inner-sphere reorganization is very small, 88 meV for self-exchange between two model cofactors computed at the density functional level of theory. Decomposing the outer-sphere reorganization free energy, we find that the solvent (aqueous ionic solution) is the primary outer-sphere medium for oxidation, contributing 0.60 eV (69%). The protein contributes only 0.27 eV (31%). For self-exchange, the solvent contribution, 0.68 eV (54%), and the protein contribution, 0.59 eV (46%), are almost equally important. The large solvent contribution is due to the slow decay of dipole reorientation of the solvent as a function of distance to the cofactor, implying that the change in the electric field upon electron transfer is not as effectively screened by the four-helix bundle protein. However, ranking the residues according to their free energy contributions, it is suggested that the reorganization free energy can be decreased by about 0.2 eV if two glutamine residues in the vicinity of the cofactor are mutated into less polar amino acids.

Thermal behavior of substituted FeCo-based metallic glasses

Three compositions of metallic glasses, Fe 58Co 24Nb 3Ta 1Mo 1B 13, Fe 61.5Co 20.5Nb 3Ta 1Mo 1B 13 and Fe 66Co 18Si 1B 15 were prepared by rapid quenching from the melt and subsequently annealed for 1 hour at 450, 650 and 750 °C. The samples were analyzed by X-ray diffraction (XRD) and Mössbauer spectroscopy. All Mössbauer spectra were fitted with a six-line pattern corresponding to the crystalline α-(FeCo) phase and a hyperfine magnetic field distribution representing the amorphous component. The Mössbauer spectra of annealed Fe 66Co 18Si 1B 15 revealed the presence of a secondary crystalline phase, namely (FeCo) 3(BSi). Moreover, the last Mössbauer spectrum in the set was fitted with an additional sextet, corresponding to the appearance of hematite in the system. It is inferred that the addition of Nb, Ta and Mo considerably delays the onset of bulk crystallization and iron oxidation in these systems. The XRD patterns are in qualitative agreement with the Mössbauer results and are consistent with a surface layer of hematite nanoparticles in the system. The activation energy of 4.34 eV for oxidation was estimated from the Mössbauer results.

Electromigration in Submicron Dual-damascene Cu/low-k Interconnects

AbstractElectromigration (EM) lifetime characteristics and failure mechanism were investigated for Cu/porous-low-k interconnects and compared to Cu/oxide. The porous low-k dielectric was JSR LKD-5109TM, an MSQ-based spin-on organosilicate material with k = 2.2. The activation energies for EM failure were found to be 0.9 - 1.0 eV for the porous MSQ and 0.8 eV for oxide while the current density exponents for both materials were found to be similar, 1.2 - 1.3. This range of activation energies are commonly associated with mass transport at the Cu/cap-layer interface and suggest a similar mass transport mechanism; interfacial diffusion. Porous MSQ structures showed the same distinct failure morphology as observed in other Cu/low-k interconnects: voiding at the cathode and lateral Cu extrusion at the anode under the cap layer, which seems to be related to the thermo-mechanical properties of Cu/low-k interconnects. The shorter lifetime characteristics of Cu/low-k interconnects comparing to Cu/oxide can be attributed to a smaller back stress, due to less thermomechanical confinement. Results of this study indicate that thermo-mechanical properties of low-k interconnects are important parameters in controlling EM reliability of Cu/low-k interconnects.

FIST—Ein symbolisches VLSI-design-system (FIST—a symbolic VLSI design-system) : Philip Dellafera. Frequenz41, 228 (1987)

Experimental measurements, including capacitance-voltage and temperature-dependent current-voltage measurements of two nitride/oxide dual-layer films, have been used to characterize the charge transport and trapping mechanisms for scaled nitride-oxide stacked films. For charge transport from the cathode electrode to the adjacent oxide or nitride, electron Fowler-Nordheim tunneling is the dominant mechanism and the tunneling barriers are 3.2 eV for oxide and 2 eV for nitride, respectively. For charge transport from the nitride to the oxide, electron tunneling with limited electron supply from the nitride/oxide injecting interfaces was observed. A new charge transport and trapping model for scaled nitride-oxide stacked films is evolved from the experimental observations. According to the model, nitride-oxide stacked films can be thought of as an oxide film with electron trapping at the nitride/oxide interface. The electron trapping reduces the leakage current and lowers the incidence of early failures for nitride-oxide stacked films.

Charge transport and trapping model for scaled nitride-oxide stacked films

Experimental measurements, including capacitance-voltage and temperature-dependent current-voltage measurements of two nitride/oxide dual-layer films, have been used to characterize the charge transport and trapping mechanisms for scaled nitride-oxide stacked films. For charge transport from the cathode electrode to the adjacent oxide or nitride, electron Fowler-Nordheim tunneling is the dominant mechanism and the tunneling barriers are 3.2 eV for oxide and 2 eV for nitride, respectively. For charge transport from the nitride to the oxide, electron tunneling with limited electron supply from the nitride/oxide injecting interfaces was observed. A new charge transport and trapping model for scaled nitride-oxide stacked films is evolved from the experimental observations. According to the model, nitride-oxide stacked films can be thought of as an oxide film with electron trapping at the nitride/oxide interface. The electron trapping reduces the leakage current and lowers the incidence of early failures for nitride-oxide stacked films.