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High-resolution X-ray diffraction of silicon-on-nothing
No full textHigh-resolution multi-crystal X-ray diffraction was employed to characterize silicon-on-nothing samples consisting of a one-dimensional periodic array of buried empty channels. p- and n-type silicon starting wafers were used for sample preparation. For the p- type samples, this periodic array gives rise to well defined Fraunhofer diffraction when the channels are normal to the scattering plane. This indicates good lattice quality of the layer containing the channels. Moreover, the lattices of the surface layer and the layer with the channels were almost indistinguishable from that of perfect silicon. Conversely, the n-type samples showed such lattice tilts and out-of-plane mosaic spreads in the surface and buried layers that Fraunhofer diffraction does not occur from the periodic array of the channels. The elucidation of this different behaviour is in progress and will most likely be fruitful after X-ray images of the same samples are taken
Dependence of Anomalous Phosphorus Diffusion in Silicon on Depth Position of Defects Created by Ion Implantation
No full textTransient enhanced diffusion of phosphorus in silicon has been investigated for implants below and above the threshold for a complete amorphization. Rapid thermal processes (electron beam) and conventional furnaces have been used for the annealing. In the case of implants below amorphization, a strong enhanced diffusion, proportional to the amount of damage produced, has been observed. The extent of the phenomenon is practically independent of the damage depth position. In contrast to this, the formation of extended defects at the original amorphous-crystalline interface makes the diffusivity strongly dependent on depth in the case of post-amorphized samples. No enhanced diffusion effect is observed if the dopant is confined in the amorphous layer, while a remarkable increase in the diffusivity is detected for the dopant located in the crystalline region beyond the amorphous-crystalline interface
Role of growth temperature on nanostructure and field emission properties of PLD thin carbon films
No full textThin carbon films have been deposited in vacuum
(∼10−4 Pa) on Si substrates by pulsed laser ablation of a
graphite target using a Nd:YAG laser operating in the near
infrared region (λ = 1064 nm). The samples have been deposited
at different substrate temperatures (T sub) ranging
from room temperature (RT) to 800°C. X-ray diffraction
analysis established the progressive formation of nanosized
graphene structures as T sub increased. In fact, film structure
evolves from almost amorphous to nanostructured phase
characterized by graphene layers oriented perpendicularly to
the film plane. The film density, evaluated by X-ray reflectivity
measurements, is strongly affected by T sub. At RT the
film density is similar to the graphite one, while it decreases
at higher T sub. The electrical properties of the samples have
been characterized by field emission measurements. The parameters
describing the emitter properties (threshold field
Eth and field enhancement factor β) have been evaluated
using variable anode-to-cathode distance method. Samples
deposited at low T sub have shown the best emission properties,
presenting lower Eth and larger β values than those
deposited at higher T sub. This is mainly attributed to thesensible density variation, which is in competition with the
slighter augment of mean nanoparticle size
Electrical and Structural Characterization of Silicon Layers Directly Doped with Boron by Excimer Laser Irradiation
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dependence of Transient Enhanced Diffusion on Defects Depth Position in Ion Implanted Silicon
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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