1,720,992 research outputs found
Peculiar failure mechanisms in GaN power transistors
Full text linkCommercial GaN power amplifiers for RF applications, made of a pair of discrete transistors for operation in Doherty configuration, failed during the HAST tests. Failure Analysis pointed out a layout-specific issue related to thermal expansion at the level of the field plates. Anyway, the search for initial degradation stages using Optical Beam Induced Resistance Change and Photon Emission Microscopy revealed a subtle second mechanism, involving Ga interdiffusion into the gate metal lines, coming from hollow pipes in GaN. Both mechanisms are discussed
Further improvements of an extended Hakki-Paoli method
No full textA modified Hakki-Paoli method, for measuring optical gain in laser diodes, proposed at the past ESREF 2017 conference is here further improved in terms of practical implementation. In particular, averaging both the spectral function and its reciprocal, over an oscillation cycle is shown to lead to the gain function replacing the calculation of maxima and minima, a cumbersome task for noisy spectra at low injection level. The ultimate goal is to get rid of the many constraints that complicate gain measurements for other than the manufacturers, and to provide a new powerful tool for laser diode characterization and diagnostics
The circular resistor (CR)-a novel structure for the analysis of VLSI contacts
No full textA novel structure, named Circular Resistor, is proposed
for extracting metal/semiconductor contact resistivity. A two-dimensional analytical solution of the system is shown in a simplified case; the complete solution is calculated by numerical simulations. Very good agreement between the analytical model and the numerical simulations was found. Regarding resolution, the Circular Resistor exhibits characteristics similar to other standard structures, but the circular shape allows to fit the actual geometry of VLSI contacts
Electrical characterization of the TiN/Ti/n+/Si (and p+/Si) interfaces by means of a circular resistor test structure
No full textA circular geometry based test structure for contact resistance measurements is introduced, together with a compact analytical model for contact resistivity extraction. The Circular Resistor (CR) structure is intended to be used for VLSI contacts that tend to a rounded shape due to lithographic effects
Tecniche di modellazione 3D per una documentazione accurata delle incisioni rupestri: confronto tra Structure from Motion e Photometric Stereo
No full text3D modelling represents a fundamental survey technique to represent archaeological
evidence. It is particularly important to draw and analyse engravings because it is more descriptive
and, somehow, objective than traditional drawings, which result interpretative and
not replicable, becoming a debatable and often controversial matter. A technique able to verify
the overlaying of signs is essential to establish the relative sequence, thus the chronology of
engravings. However, the techniques are more than one and give different results. The paper
tries to empirically compare SfM and PS methods to understand how they work surface representation
and what are their specificities in a difficult context such as the Pianaùra engravings.
The aim of the paper is to verify the accuracy of the techniques. Three paths are pursued: the
first applies analyses of pure quantitative data, such as counting the number of points or faces
built and so on; the second aims to verify quantitatively distortions by geometric measurements
analysis; the third is a visual quality test, which focuses on users’ perception of 3D models.
It can be concluded that the different fields of application and the different purposes of the
research enhance the different specificities of the two techniques
Anodic Gold corrosion in plastic encapsulated devices
No full textExperimental results of Gold metallization failures in semiconductor devices due to the corrosion of Gold in the absence of a complexing medium or contaminants are reported. In particular, we show the corrosion of anodically biased lines which was observed on unpassivated plastic encapsulated high-frequency transistors and on passivated linear integrated circuits operating at 85°C, 85% R.H., for a few thousend hours
Electron holographic observations of the electrostatic field associated with thin reverse-biased p-n junctions
No full textA new method has been devised for investigation by TEM of th electrostatic microfield associated with reverse biase p-n junctions. By means of electron holography and optical inteferometry it is possible to obtain on the reconstructed images two-dimensional representations of the projected potential distribution inside and outside the specime
Identifying the lights position in photometric stereo under unknown lighting
No full textReconstructing the 3D shape of an object from a set of images is a classical problem in Computer Vision. Photometric stereo is one of the possible approaches. It stands on the assumption that the object is observed from a fixed point of view under different lighting conditions. The traditional approach requires that the position of the light sources is accurately known. It has been proved that the lights position can be estimated directly from the data when at least 6 images of the observed object are available. In this paper, we present a Matlab implementation of the algorithm for solving the photometric stereo problem under unknown lighting, and propose a simple shooting technique to solve the bas-relief ambiguity
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