A5072448656- Semiconductor Quantum Structures and Devices
- Surface and Thin Film Phenomena
- nanoparticles nucleation surface interactions
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Theoretical and Computational Physics
- Nanowire Synthesis and Applications
- Advanced Semiconductor Detectors and Materials
- Advanced Chemical Physics Studies
- Force Microscopy Techniques and Applications
- Material Dynamics and Properties
- Semiconductor materials and interfaces
- Silicon Nanostructures and Photoluminescence
- Advancements in Semiconductor Devices and Circuit Design
- Polymer crystallization and properties
- Ion-surface interactions and analysis
- Solidification and crystal growth phenomena
- Integrated Circuits and Semiconductor Failure Analysis
- Graphene research and applications
- Surface Chemistry and Catalysis
- Chemical and Physical Properties of Materials
- Advanced Materials Characterization Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- ZnO doping and properties
- Electronic and Structural Properties of Oxides
University of Rome Tor Vergata
2015-2025
Istituto Nazionale per la Fisica della Materia
1997-2007
University of Arkansas at Fayetteville
2007
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
1985-1990
Politecnico di Milano
1990
Institute of Structure of Matter
1987-1989
Istituto Nazionale di Fisica Nucleare
1986
Sapienza University of Rome
1986
Scuola Internazionale Superiore di Studi Avanzati
1984-1985
By making a comparison between the Mn K-edge absorption of (${\mathrm{MnO}}_{4}$${)}^{\mathrm{\ensuremath{-}}}$ and [Mn(${\mathrm{H}}_{2}$O${)}_{6}$${]}^{2+}$ complexes in aqueous solution we obtain an experimental determination energy extent type-II multiple-scattering (MS) regime that is substantially wider than expected. Theoretical calculations based on MS formalism support this conclusion. We also recognize three regions spectra these complexes: full region, where numerous or infinite...
The oxygen K-edge x-ray-absorption near-edge structure of stoichiometric NiO has been measured, using partial electron yield, at the ``grasshopper'' line Frascati synchrotron-radiation facility. main features spectrum in multiple-scattering region over 50-eV energy range beyond threshold are well predicted by full one-electron theory. interpretation fine details requires a many-body picture, fact, results agreement with description as system that cannot be classified standard mixed-valence system.
We have investigated by atomic force microscopy and scanning tunneling subsequent stages of the heteroepitaxy InAs on GaAs(001) from initial formation strained two-dimensional wetting layer up to development three-dimensional quantum dots. provide evidence structural features that play a crucial role in two- transition discuss their contribution final morphology self-assembled nanoparticles. A model is suggested for phase at critical thickness consisting an intermixed...
Up to now, the time dependence of volume fraction during a first-order phase transition has been often described by Avrami's model, in which nucleation is assumed occur randomly infinite volume. In this paper we present computer simulation order verify validity kinetics cases random and nonrandom distribution germ nuclei. Our results indicate that correct solution, provided nuclei extended computed including so-called phantom It also shown general solution form functional volumes appropriate...
Synchrotron radiation (SR) photoemission and x-ray photoelectron spectroscopy (XPS) are used to reveal the presence of Si–OH species at surface aged silica. SR Si 2p spectra, recorded in photon energy range 130 eV≤hν≤240 eV, show coexistence Si–O bonding states states, latter being marked by a component 105.2 eV binding energy. The intensity ratio I[Si–OH]/I[Si–O] varies monotonically from 0.24 0.77 with increasing kinetic 15 135 respectively. On contrary, no sign silanol groups is evident...
We studied the temperature dependence of two-dimensional to three-dimensional growth transition in InAs∕GaAs(001) heteroepitaxy by means reflection high energy electron diffraction and atomic force microscopy. The observed shift higher InAs deposition times, at temperatures above 500°C, is not a change critical thickness for islanding, which instead, constant 450–560°C range. Consequently, In-Ga intermixing surface interface strain have negligible on this
We have investigated, by means of atomic force microscopy, the complete evolution InAs∕GaAs(001) quantum dots as a function deposited InAs. Direct evidence is found for step erosion nucleated onto edge and an estimate eroded volume provided. By studying InAs coverage, we show that wetting layer contribution confined within narrow range coverage around two- three-dimensional transition.
A complete description of Ge growth on vicinal Si(001) surfaces in the angular miscut range 0\ifmmode^\circ\else\textdegree\fi{}--8\ifmmode^\circ\else\textdegree\fi{} is presented. The key role substrate vicinality clarified from very early stages deposition up to nucleation 3D islands. By a systematic scanning tunneling microscopy investigation we are able explain competition between step-flow and 2D progressive elongation islands along direction [110]. Using finite element calculations,...
In the Johnson-Mehl-Avrami-Kolmogoroff theory, concepts of phantom nuclei and extended space, which caused not a little confusion among investigators, is an unavoidable accident theory. A straightforward mathematical derivation that presented. Besides, some interesting important physical consequences related to have been investigated.
Step instability and surface mass transport strongly influence the kinetics of two- to three-dimensional (2D–3D) transition in InAs/GaAs self-assembly epitaxy. In this paper we report evidence step erosion quantum dots (QDs) nucleated on edges for samples having different morphologies explosive nucleation 3D QDs triggered by it. Related issues such as temperature dependence critical thickness, volume transport, scaling behaviour are illustrated means RHEED AFM measurements data analysis...
We present a detailed atomic-force-microscopy study of the effect annealing on InAs/GaAs(001) quantum dots grown by molecular-beam epitaxy. Samples were at low growth rate $500\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ with an InAs coverage slightly greater than critical thickness and subsequently annealed several temperatures. find that immediately quenched samples exhibit bimodal size distribution high density small $(<50\text{ }{\text{nm}}^{3})$ while temperatures $420\text{...
Starting with the basic definition, a short description of few relevant physical quantities playing role in growth process heteroepitaxial strained systems, is provided. As such, paper not meant to be comprehensive survey but present connection between Stranski-Krastanov mechanism nanostructure formation and principles nucleation growth. The elastic field described context continuum elasticity theory, using either analytical models or numerical simulations. results are compared selected...
The synthesis, spectroscopic, and optical properties of the water-soluble phosphorus complex a 2-sulfonato-10-(4-sulfonatophenyl)-5,15-dimesitylcorrole have been investigated. compound was prepared by adopting novel strategy for corrole sulfonation, leading to regioselective isomer in an almost quantitative yield. coordination has key role determining substitution pattern, limiting formation poly-substituted species, which affected reaction free base. resulting shows excellent terms emission...
The two- to three-dimensional growth transition in the InAs/GaAs(001) heterostructure has been investigated by atomic force microscopy. kinetics of density three dimensional quantum dots evidences two thresholds at 1.45 and 1.59 ML InAs coverage, corresponding separate families, small large. Based on scaling analysis, such families are characterized different mechanisms aggregation, involving change critical nucleus size. Remarkably, ones give rise a wealth "monomers" through erosion step...
Many manifestations of natural processes give rise to interesting morphologies; it is all too easy cite the corrugation Earth's surface or planets in general. However, limiting ourselves 2D cases, morphology which crystal growth gives also intriguing. In particular, study some characteristics cluster projection 2D, namely shapes speckles (fractal dimension their rims) distribution areas. Recently, for instance, has been shown that size cumulative function (cdf) ``voids'' a corrole film on...
We analyzed by atomic force microscopy self-assembled quantum dots of InAs on GaAs(001) in a series samples prepared molecular beam epitaxy (MBE). Two different growth procedures have been applied, namely, the usual continuous and migration-enhanced growth. At equal depositions InAs, larger than critical thickness for two- to three-dimensional transition, marked differences are found evolution nanoparticle density volume, despite same set parameters were used. Above 2 ML, small fraction...
We discuss the self-aggregation process of InAs and Si–Ge quantum dots (QDs) on natural patterned GaAs(001) Si(001) Si(111) surfaces, with reference to our recent studies scanning tunnelling atomic force microscopy current experimental theoretical works. Various methods for obtaining naturally structured surfaces are briefly surveyed, as patterning formed by surface instability strain in mismatched heteroepitaxy, latest pre-patterning growth at selected sites discussed. Basic topics also...
In this article some results regarding film growth considered as a stochastic process of dots are reviewed. The central concept the theory described in initial part is evaluation exclusion probability, i.e. probability that no found given region surface. This reviewed to certain extent for both correlated and uncorrelated and, moreover, distinguishable classes dots. theoretical framework allows one tackle nucleation films ruled by diffusion adspecies. specific instance has been employed...