Luca Reggiani

Bio: Luca Reggiani is an academic researcher from Polytechnic University of Milan. The author has contributed to research in topics: Monte Carlo method & Noise (electronics). The author has an hindex of 26, co-authored 272 publications receiving 2711 citations. Previous affiliations of Luca Reggiani include University of California & University of Szeged.

Electron effective masses and lattice scattering in natural diamond

Abstract: We report experimental evidence of the Si-like conduction band of natural diamond. A Monte Carlo analysis of electron drift velocity data enables for the first time the electron effective masses to be determined.

Pseudo-chaotic time hopping for UWB impulse radio

Abstract: In this paper, we propose a pseudo-chaotic modulation suitable for ultrawide-bandwidth impulse-radio communication systems. The coding scheme is based upon controlling the symbolic dynamics of a chaotic map for encoding the digital information to be transmitted. The pseudo-chaotic time hopping enhances the spread-spectrum characteristics of the system, by removing most periodic components from the transmitted signal. A maximum-likelihood detector for the proposed scheme is presented and its scalability features are illustrated. Finally, theoretical performance bounds for both soft and hard Viterbi decoding are derived and compared with the simulation results.

Hole-drift velocity in natural diamond

Abstract: The drift velocity of holes in natural diamond is analyzed for a wide range of temperatures $85\ensuremath{\le}T\ensuremath{\le}700$ K and fields ${10}^{2}lEl6\ifmmode\times\else\texttimes\fi{}{10}^{4}$ V/cm applied parallel to $〈100〉$ and $〈110〉$ crystallographic directions. Experiments are carried out with the time-of-flight technique, and theory uses a Monte Carlo method. The microscopic interpretation is based on a two-spherical and parabolic band model and considers lattice scattering only. Values ${m}_{h}=1.1{m}_{o}$ and ${m}_{l}=0.3{m}_{o}$ for heavy-and light-hole effective masses are found.

Microscopic simulation of electronic noise in semiconductor materials and devices

Abstract: We present a microscopic interpretation of electronic noise in semiconductor materials and two-terminal devices. The theory is based on Monte Carlo simulations of the carrier motion self-consistently coupled with a Poisson solver. Current and voltage noise operations are applied and their respective representations discussed. As application we consider the cases of homogeneous materials, resistors, n/sup +/nn/sup +/ structures, and Schottky-barrier diodes. Phenomena associated with coupling between fluctuations in carrier velocity and self-consistent electric field are quantitatively investigated for the first time. At increasing applied fields hot-carrier effects are found to be of relevant importance in all the cases considered here. As a general result, noise spectroscopy is found to be a source of valuable information to investigate and characterize transport properties of semiconductor materials and devices. >

Pseudo-chaotic communication method exploiting symbolic dynamics

Abstract: A pseudo-chaotic coding/modulation method. The coding method exploits symbolic dynamics of a chaotic map at the transmitter to encode data. The encoding synthesizes the chaotic map based upon the data to be transmitted. In a preferred embodiment, pseudo-chaotic iterates are generated from a digital implementation of a Bernoulli shift map. The output of the shift map is translated by a mapping, preferably implemented by a digital signal processor, to allow transitions between states in a transmitted signal to differ, and the translated map is used to drive a modulator (for example PPM, FSK, PSK, QAM, etc.). In the specific case of pulse-position modulation (PPM) the translated map is used to modulate pulse train positions within a periodic synchronization frame. The preferred embodiment uses a shift register to implement an approximation of the Bernoulli shift map acting as a form of convolutional code with a number of states equal to the symbolic states defined on the chaotic map. A receiver may use fewer states and still decode the data signal, allowing receiver scalability.

Shot noise in mesoscopic conductors

Abstract: Theoretical and experimental work concerned with dynamic fluctuations has developed into a very active and fascinating subfield of mesoscopic physics. We present a review of this development focusing on shot noise in small electric conductors. Shot noise is a consequence of the quantization of charge. It can be used to obtain information on a system which is not available through conductance measurements. In particular, shot noise experiments can determine the charge and statistics of the quasiparticles relevant for transport, and reveal information on the potential profile and internal energy scales of mesoscopic systems. Shot noise is generally more sensitive to the effects of electron–electron interactions than the average conductance. We present a discussion based on the conceptually transparent scattering approach and on the classical Langevin and Boltzmann–Langevin methods; in addition a discussion of results which cannot be obtained by these methods is provided. We conclude the review by pointing out a number of unsolved problems and an outlook on the likely future development of the field.

The Quantum Theory of Light

Abstract: (b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

Transparent conductors as solar energy materials: A panoramic review

Abstract: Transparent conductors (TCs) have a multitude of applications for solar energy utilization and for energy savings, especially in buildings. The largest of these applications, in terms of area, make use of the fact that the TCs have low infrared emittance and hence can be used to improve the thermal properties of modern fenestration. Depending on whether the TCs are reflecting or not in the near infrared pertinent to solar irradiation, the TCs can serve in “solar control” or “low-emittance” windows. Other applications rely on the electrical conductivity of the TCs, which make them useful as current collectors in solar cells and for inserting and extracting electrical charge in electrochromic “smart windows” capable of combining energy efficiency and indoor comfort in buildings. This Review takes a “panoramic” view on TCs and discusses their properties from the perspective of the radiative properties in our ambience. This approach leads naturally to considerations of spectral selectivity , angular selectivity , and temporal variability of TCs, as covered in three subsequent sections. The spectrally selective materials are thin films based on metals (normally gold or titanium nitride) or wide band gap semiconductors with heavy doping (normally based on indium, tin, or zinc). Their applications to energy-efficient windows are covered in detail, experimentally as well as theoretically, and briefer discussions are given applications to solar cells and solar collectors. Photocatalytic properties and super-hydrophilicity are touched upon. Angular selective TCs, for which the angular properties are caused by inclined columnar nanostructures, are then covered. A discussion of TC-like materials with thermochromic and electrochromic properties follows in the final part. Detailed treatments are given for thermochromic materials based on vanadium dioxide and for electrochromic multi-layer structures (incorporating TCs as essential components). The reference list is extensive and aims at giving an easy entrance to the many varied aspects of TCs.

Low-Pressure, Metastable Growth of Diamond and "Diamondlike" Phases

Abstract: Diamond may be grown at low pressures where it is the metastable form of carbon. Recent advances in a wide variety of plasma and electrical discharge methods have led to dramatic increases in growth rates. All of these methods have certain aspects in common, namely, the presence of atomic hydrogen and the production of energetic carbon-containing fragments under conditions that support high mobilities on the diamond surface. Some understanding of the processes taking place during nucleation and growth of diamond has been achieved, but detailed molecular mechanisms are not yet known. Related research has led to the discovery of a new class of materials, the "diamondlike" phases. Vapor-grown diamond and diamondlike materials may have eventual applications in abrasives, tool coatings, bearing surfaces, electronics, optics, tribological surfaces, and corrosion protection.

Plasma-liquid interactions: A review and roadmap

Abstract: Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.