Polytechnic University of Milan

About: Polytechnic University of Milan is a education organization based out in Milan, Italy. It is known for research contribution in the topics: Finite element method & Population. The organization has 18231 authors who have published 58416 publications receiving 1229711 citations. The organization is also known as: PoliMi & L-NESS.

On the bremsstrahlung origin of hot-carrier-induced photons in silicon devices

Abstract: Spectrally resolved absolute measurements of hot-carrier-induced photon emission in silicon are reported. In order to avoid uncertainties in geometrical and physical parameters, the simplest conceivable device, an avalanching p-n junction, was used. A photon emission efficiency of 2.9*10/sup 5/ photons with energy higher than 1.14 eV per carrier crossing the junction, independent of the lattice temperature down to 20 K, was measured. On the basis of these results the bremsstrahlung origin of the hot-carrier-induced light emission is critically reviewed. >

Assessing relations between Circular Economy and Industry 4.0: a systematic literature review

Abstract: Industry 4.0 (I4.0) and Circular Economy (CE) are undoubtedly two of the most debated topics of the last decades. Progressively, they gained the interest of policymakers, practitioners and scholars...

Threshold switching mechanism by high-field energy gain in the hopping transport of chalcogenide glasses

Abstract: Chalcogenide glasses are widely used in phase-change nonvolatile memories and in optical recording media for their ability to rapidly change their structure to crystalline, thus obtaining different electrical resistance and optical reflectivity. Chalcogenide glasses universally display threshold switching, that is a sudden, reversible transition from a high-resistivity state to a low-resistivity state observed in the current-voltage $(I\text{\ensuremath{-}}V)$ characteristic. Since threshold switching controls the operating voltage and speed of phase-change memories, the predictability of the switching voltage, current, and speed is of critical importance for selecting the proper chalcogenide material for memory applications. Although threshold switching has long been recognized to be an electronic process with an intimate relation to localized states, its detailed physical mechanism is still not clear. In this work, threshold switching is explained by the field-induced energy increase in electrons in their hopping transport, moderated by the energy relaxation due to phonon-electron interaction. The energy increase leads to an enhancement of conductivity and a collapse of the electric field within the amorphous chalcogenide layer, accounting for the observed negative differential resistance at switching. Threshold switching is found to obey to a constant electrical-power condition. The proposed model generally applies to low-mobility semiconductors featuring a deep Fermi level and hopping-type conduction, and can predict the thickness, temperature, and material dependence of threshold voltage and current.

Frequency dependence on bias current in 5 GHz CMOS VCOs: impact on tuning range and flicker noise upconversion

Abstract: The tuning curve of an LC-tuned voltage-controlled oscillator (VCO) substantially deviates from the ideal curve 1//spl radic/(LC(V)) when a varactor with an abrupt C(V) characteristic is adopted and the full oscillator swing is applied directly across the varactor. The tuning curve becomes strongly dependent on the oscillator bias current. As a result, the practical tuning range is reduced and the upconverted flicker noise of the bias current dominates the 1/f/sup 3/ close-in phase noise, even if the waveform symmetry has been assured. A first-order estimation of the tuning curve for MOS-varactor-tuned VCOs is provided. Based on this result, a simplified phase-noise model for double cross-coupled VCOs is derived. This model can be easily adapted to cover other LC-tuned oscillator topologies. The theoretical analyses are experimentally validated with a 0.25 /spl mu/m CMOS fully integrated VCO for 5 GHz wireless LAN receivers. By eliminating the bias current generator in a second oscillator, the close-in phase noise improves by 10 dB and features -70 dBc/Hz at 10 kHz offset. The 1/f/sup 2/ noise is -132 dBc/Hz at 3 MHz offset. The tuning range spans from 4.6 to 5.7 GHz (21%) and the current consumption is 2.9 mA.