Materials Literature
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Computer simulation of the temperature, dose, and trap filling effects of transient RIC is carried out by means of the Rose-Fowler-Vaisberg formalism. These combined effects allow to determine the trap distribution type exponential or Gaussian, an available data favouring the former. It is also shown that the usual Ro…
Dielectric properties of hexagonal ferrites BaFe12O19, BaTi2Fe4O11, and BaSn2Fe4O11 are examined from 4.2 to 500 K. BaFe12O19 shows low dielectric constant and conductivity, while BaTi2Fe4O11 shows large dielectric constant and conductivity. On the other hand BaSn2Fe4O11 which has the same crystal structure as BaTi2Fe…
At low temperatures the compounds Bi2WO6 and Bi2MoO6, like many other related layered ferro-electrics, are electrically polar and transform to nonpolar state on heating. These phase transitions, however, are not ordinary ferroelectric ones and have a reconstructive nature. The two compounds undergo also additional pha…
Measurements have been made of Raman scattering from pure single crystals of NaCl at several temperatures in the range 300--1025 K. With reference to the 2TA(X) and 2LA(X) bands, which are well resolved at all temperatures, it has been found that the observed intensities are much greater than those anticipated by the…
A novel AlAs/n-GaAs superlattice structure, in which the GaAs midlayers are selectively doped with Si, has been designed as an electron supplying layer for two-dimensional electron gas (2DEG) systems to obtain a high sheet carrier concentration, using a simple Kronig–Penney model calculation. The optimized structure i…
The pseudo-binary compounds Gd(Fe 1- x Mn x ) 2 have been investigated. The crystal structures are C-15 for x ≤0.2 and x ≥0.9, X-structure for 0.4≤ x ≤0.7 and mixture (C-15 and X-structure) for x =0.3 and 0.8, respectively. The measurements of X-ray diffraction, magnetic measurement, NMR and Mössbauer effect were carr…
The results of an investigation of thermal effects on the fluorescence spectra of Ti3+ in sapphire are presented. As-grown samples synthesized by the Czochralski method were found to exhibit a fluorescence band characteristic of Ti4+. After thermal annealing this band was greatly reduced and the Ti3+ fluorescence was…
The bonding in Fe2(CO)9 is analyzed using an SCF wave function for a large basis set. There is no direct Fe–Fe metal–metal bond. The bridging CO’s hold the two Fe(CO)3 fragments together by σ donation into the empty Fe–Fe dπ orbital and metal donation from the dπ* orbital into the CO 2π* orbital. The bonding of the te…
Recent work has indicated that the single-scattering theory of x-ray absorption may be valid down to much closer to the edge than previously thought. It is in this region that the plane-wave approximation used in the standard extended x-ray-absorption fine structure analysis breaks down. Using a simple reformulation,…
Nitrogen-doping and -implantation studies reveal a new photoluminescence spectrum in silicon with a no-phonon transition at 0.746 eV. The line exhibits $^{14}\mathrm{N}$${,}^{15}$N and $^{12}\mathrm{C}$${,}^{13}$C isotope splittings showing that single nitrogen and carbon atoms are incorporated in the defect. Zeeman m…
The electrical resistivity of layerd crystalline GeSe has been investigated up to a pressure of 100 kbar and down to liquid-nitrogen temperature by use of a Bridgman anvil device. A pressure-induced first-order phase transition has been observed in single-crystal GeSe near 6 GPa. The high-pressure phase is found to be…
The Mn-intercalated transition metal dichalcogenides Mn 1/4 NbS 2 and Mn 1/4 TaS 2 have been found to be easy-plane type ferromagnets from the magnetization curves, while the magnetization curve of Mn 1/4 NbSe 2 shows a spin flopping behavior, suggesting a helical spin structure along the c -axis. The valency of Mn io…
The dielectric function of orthorhombic GeS has been measured ellipsometrically in the 1.66--5.6-eV photon-energy region as a function of temperature between 84 and 500 K. The second derivatives with respect to frequency of the real and imaginary parts of the dielectric function, obtained numerically from the measured…
The one-dimensional band structures of (tetrabenzoporphyrinato) Ni (II) and (phthalocyaninato) Ni (II) were calculated. The reported band structures include the effects of the stacking perturbation and of the overlap between nearest neighbors. The basis functions for the intermolecular integrals were obtained from a d…
The structure of thin silver films, grown under varying conditions of ion bombardment, are compared by means of their measured structural, optical, and electrical properties. Both the x-ray diffraction results and the dielectric-function measurements suggested that there are voids in our films and that their volume fr…
Theoretical analysis of the defect trapping of ion-implanted hydrogen in metals has been extended in two respects. A new transport formalism has been developed which takes account not only of the diffusion, trapping, and surface release of the hydrogen, which were included in earlier treatments, but also the diffusion…
The characteristic 1.54-μm emission from the rare-earth element erbium implanted in GaAs, InP, and GaP was investigated through 10-K photoluminescence essentially as a function of anneal temperature, time, and method. The strip-heater, forming-gas, and quartz-ampoule anneal methods were utilized in the range of 400 to…
Unoccupied electronic states at the diamond (111) surface are studied by measuring both bulk- and surface-sensitive C 1s partial-yield soft-x-ray absorption spectra. Several absorption features are observed in the bulk band gap below the 289.19-eV bulk-C 1s absorption edge. They are associated with transitions from th…
Stress was determined in oxidized porous silicon layers using x-ray diffraction to measure the substrate curvature. Stress is always compressive and its magnitude depends on oxide quality. The maximum value is reached when the oxide obtained from porous silicon is densified by a high-temperature process and is equival…
Very thin gold films were prepared on glass by ion plating (IP) and by conventional evaporation (CE). Below a certain thickness—∼9 nm for IP and ∼15 nm for CE—the films comprised a metal network; above this thickness we found uniform films. Optical properties were recorded by spectrophotometry. Conspicuous near-infrar…