36 research outputs found
Dispersion force for materials relevant for micro and nanodevices fabrication
The dispersion (van der Waals and Casimir) force between two semi-spaces are
calculated using the Lifshitz theory for different materials relevant for micro
and nanodevices fabrication, namely, gold, silicon, gallium arsenide, diamond
and two types of diamond-like carbon (DLC), silicon carbide, silicon nitride
and silicon dioxide. The calculations were performed using recent experimental
optical data available in the literature, usually ranging from the far infrared
up to the extreme ultraviolet bands of the electromagnetic spectrum. The
results are presented in the form of a correction factor to the Casimir force
predicted between perfect conductors, for the separation between the
semi-spaces varying from 1 nanometre up to 1 micrometre. The relative
importance of the contributions to the dispersion force of the optical
properties in different spectral ranges is analyzed. The role of the
temperature for semiconductors and insulators is also addressed. The results
are meant to be useful for the estimation of the impact of the Casimir and van
der Waals forces on the operational parameters of micro and nanodevices
A European proficiency test on thin film tandem photovoltaic devices
A round robin proficiency test RR PT on thin film multi junction MJ photovoltaic PV cells was run between 13 laboratories within the European project CHEETAH. Five encapsulated PV cells were circulated to participants for being tested at Standard Test Conditions STC . Three cells were a Si amp; 956;c Si tandem PV devices, each of which had a different short circuit current ratio between the top junction and the bottom one; the remaining two cells were single junction PV devices made with material representative of the individual junctions in the MJ cells. The RR PT s main purpose was to assess the capability of the participating laboratories, in terms of employed facilities and procedures, to test MJ PV devices. Therefore, participant
Electron energy-loss spectroscopy (EELS) ; comparison with X-ray analysis
Analytical electron microscopy offers two main techniques of interest to materials science : electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray analysis (EDX). The scientist is confronted with the choice of one of the two for the problem under consideration, although it is possible to employ both simultaneously. It is therefore important to know what to expect from each of the two techniques to assess which one is more likely to yield the desired information. Here both are compared to provide help in making that decision. The various aspects are illustrated with recent applications of both techniques in the research on interfaces in ceramics. Emphasis is put on the analysis of additional information contained in EELS, because this contributes to the understanding of bonding and chemistry inside the specimen