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Nanoscale imaging of the electrical properties of CaCu3Ti4O12 ceramics has been performed using scanning impedance microscopy. Two kinds of electrical inhomogeneity are detected, namely, depletion layers at grain boundaries and calcium titanate inclusions, both of which are more resistive than the bulk of the grains. Energy filtered transmission electron microscopy was used to estimate the chemical composition of the inclusions. [ABSTRACT FROM AUTHOR]

Silicon nanoclusters were formed in plasma-enhanced chemical vapor deposited substoichiometric silicon oxide films by annealing at 1100 °C for 1/2 h as a function of different deposition parameters. The samples were analyzed by energy filtered transmission electron microscopy and Rutherford backscattering. At any deposition condition, the clustered silicon concentration is significantly lower than the initial silicon excess concentration. This behavior is explained by taking into account the free energy difference between the metastable SiO and stable SiO2 phase and the strain energy associated with the different atomic densities of Si and SiO2. [ABSTRACT FROM AUTHOR]

The effect of interstitial trapping by surface nanovoids, induced by He ion implantation in crystalline Si, is described. The difference with respect to the effects induced by the deep void layer is evidenced and discussed. Interstitial trapping is investigated by studying the diffusion and the electrical activation of shallow boron implanted in Si. B and He ion implantations were performed on Czochralski bulk and silicon-on-insulator samples in order to isolate the void surface region from the deep void layer. A remarkable reduction of B diffusion is recorded near half the projected range (Rp) of He implantation, which leads to a boxlike shape in the distribution of mobile and electrically active B. Surface nanovoids (2–3 nm in size) cause the observed B diffusivity reduction through an enhanced recombination of self-interstitials. Moreover, these surface nanovoids do not hinder the B electrical activation, being the electrically active B dose comparable for the He implanted and the He-free samples. This peculiar effect of He coimplantation at about half the Rp could be used as an efficient interstitial trapping in defect engineering during Si based device processing. [ABSTRACT FROM AUTHOR]

Si(100) samples, preamorphized to a depth of ∼30 nm using 20 keV Xe ions to a nominal fluence of 2×1014 cm-2 were implanted with 1 and 3 keV BF2 ions to fluences of 7×1014 cm-2. Following annealing over a range of temperatures (from 600 to 1130 °C) and times the implant redistribution was investigated using medium-energy ion scattering (MEIS), secondary ion mass spectrometry (SIMS), and energy filtered transmission electron microscopy (EFTEM). MEIS studies showed that for all annealing conditions leading to solid phase epitaxial regrowth, approximately half of the Xe had accumulated at depths of 7 nm for the 1 keV and at 13 nm for the 3 keV BF2 implant. These depths correspond to the end of range of the B and F within the amorphous Si. SIMS showed that in the preamorphized samples, approximately 10% of the F migrates into the bulk and is trapped at the same depths in a ∼1:1 ratio to Xe. These observations indicate an interaction between the Xe and F implants and a damage structure that becomes a trapping site. A small fraction of the implanted B is also trapped at this depth. EXTEM micrographs suggest the development of Xe agglomerates at the depths determined by MEIS. The effect is interpreted in terms of the formation of a volume defect structure within the amorphized Si, leading to F stabilized Xe agglomerates or XeF precipitates. [ABSTRACT FROM AUTHOR]

The kinetics of the amorphous-to-crystal transition in Ge2Sb2Te5 thin films have been studied through in situ transmission electron microscopy analyses. By following the time evolution of the grain density and size, the growth velocity and the nucleation rate have been separately measured at different annealing temperatures. Activation energies of 2.9±0.5 eV and 2.3±0.4 eV have been obtained for the nucleation rate and the growth velocity, respectively. The barrier energy for the nucleation of a critical nucleus ΔG* has been evaluated, and the scalability of phase change nonvolatile memories has been estimated. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Nanostructured carbon and carbon–TiOx films produced by supersonic cluster beam deposition have been characterized by spatially resolved (0.5 μm lateral resolution) photoemission spectroscopy with synchrotron light. We have found that pure and TiOx-containing nanostructured carbon is modified under high flux UV exposure showing the onset of a metallic character near the Fermi level. We have studied the spectroscopic features, the spatial confinement, and the kinetics of this metallization process of the irradiated regions. This effect allows one to write metallic patterns in the TiOx-containing films with a submicrometric resolution and with a fast kinetic. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We construct atomistic models of the Si(100)–SiO[sub 2] interface in accord with available experimental data. Combining classical and first-principles simulation methods, we generate transition structures from crystalline silicon to disordered SiO[sub 2]. The generation procedure accounts for the density of coordination defects, the amount and location of partially oxidized Si atoms, and the mass density profile, as measured in electron-spin-resonance, photoemission, and x-ray reflectivity experiments, respectively. A variety of model interfaces are obtained, differing by the degree of order in the transition region. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Praseodymium oxide (Pr[SUB2]O[SUB3]) thin films have been deposited on Si(100) substrates by metalorganic chemical vapor deposition using praseodymium tris-2,2,6,6-tetramethyl-3,5-heptandionate as source material. Film structural, morphological, and compositional characterizations have been carried out. Dielectric properties have been studied as well by capacitance-voltage and current-voltage measurements on metal-oxide-semiconductor capacitors of several areas. The Pr[SUB2]O[SUB3] films have shown a dielectric constant ∊=23-25 and a leakage current density of 8.8×10[SUP-8] A/cm[SUP2] at 11 V. [ABSTRACT FROM AUTHOR]

We model Si 2p core-level shifts at Si-(ZrO[SUB2])[SUB2](SiO[SUB2])[SUB1-x] interfaces for varying Zr content x. Using a first-principles approach, we calculate Si 2p shifts for a model interface and for cluster models, and establish the validity of a linear dependence of these shifts on both the number of second-neighbor Zr atoms and the O coordination of these Zr atoms. Applying this relation to model structures of amorphous Zr silicates generated by classical molecular dynamics, we find that the Si 2p) line shifts to lower binding energies with increasing Zr content x, in accord with experimental data. [ABSTRACT FROM AUTHOR]

The structural and optical properties of β-FeSi[sub 2] precipitates in Si have been analyzed. Float zone Si samples were implanted at 250 °C with 350 keV Fe ions to fluences in the range 1-5x10[sup 15]/cm[sup 2] and annealed in vacuum at 800 °C for times up to 24 h. Detailed morphological analyses of these samples, using transmission electron microscopy, reveal the presence of (i) a band of small (with a diameter <30 nm) highly strained β-FeSi[sub 2] precipitates centered at a depth of ∼150 nm, (ii) a band of large (>100 nm diameter) fully relaxed β-FeSi[sub 2] precipitates centered at a depth of ∼320 nm, and (iii) residual extended defects. A sharp photoluminescence peak at 1.54 μm is measured at 17 K. This peak remains unchanged when the region containing the small precipitates is removed, using Ar sputtering. On the other hand, it is also fully suppressed when the large precipitates region is removed and a high concentration of extended defects remains in the samples. This allowed us to identify the large unstrained precipitates as the main sources of the 1.54 μm luminescence. Finally, we found that carrier recombination within iron precipitates is characterized by a weak oscillator strength resulting in a long decay lifetime of the 1.54 μm signal at 17 K (∼60 μs) and in a strong temperature quenching of the luminescence yield. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]