Papers by Salvatore Iannotta
Journal of Physical Chemistry C, 2012
We demonstrate for the first time the ability to selectively sensitize a specific area of nanorod... more We demonstrate for the first time the ability to selectively sensitize a specific area of nanorods in a forest, by kinetically activated processes, induced by a supersonic beam source. The experiments have been carried out on forests of ZnO grown by vapor phase deposition on aluminum doped ZnO. The highly supersonic beam, produced by seeding TiOPc in He, achieves a molecular kinetic energy larger than 15 eV. By exposing the ZnO forest at different angles with respect to the beam direction, we sensitized the nanorods on different specific sites, leaving the other parts completely clean, as confirmed by SEM and HR-TEM studies. The effective sensitization is demonstrated by photoexcitation spectroscopies, where the PL spectra indicate efficient energy transfer from the TiOPc molecule to the ZnO nanorods. Since this kinetical functionalization approach does not need molecules with specific linkers, the present results pave the way to novel multifunctional sensitization processes that we envisage to be uniquely suitable for hybrid photovoltaics, sensing, and biomedical applications.
Solid State Phenomena, 2002
Semiconductor Science and Technology, 2014
Logic elements endowed with memory are realized with two types of memristors: organic and inorgan... more Logic elements endowed with memory are realized with two types of memristors: organic and inorganic ones. The organic devices are based on a polyaniline/polyethylene oxide heterostructure, while the inorganic ones are based on a Pt/Al 2 O 3 /Ti heterostructure. The memristors are characterized by measuring cyclic voltage-current characteristics. They are then used to make AND gates showing memory abilities, exhibiting different behaviors. In the case of the inorganic devices the OFF/ON transitions are very fast when two inputs are applied simultaneously, while they are slow, with a gradual increase of the conductivity, in the case of the organic devices. The two types of devices are suggested as logic elements for future neuromorphic computers combining memory and processing properties.
Materials Science Forum, 2003
Organic Photonic Materials and Devices III, 2001
ABSTRACT Recent results obtained in the growth of organic materials by supersonic molecular beams... more ABSTRACT Recent results obtained in the growth of organic materials by supersonic molecular beams (SuMBE) are presented. Compared to other vacuum deposition methods, it allows an accurate control on the initial state (kinetic energy, momentum, flux, etc.) of the molecules during the deposition process. We show that such feature can be efficiently exploited to prepare films, the structure and morphology of which resemble those single crystals, therefore achieving unprecedented control on their optical and electronic properties even for relatively thick samples (&amp;amp;gt; 500 nm). We also report on the use of SuMBE for processes of co-deposition with the aim of functionalizing or doping organic semiconductors. We achieved co-depositions of a p-type semiconductor, as metal phthalocyanines, with an n- type semiconductor, as fullerenes, without phase segregation between the two compounds and with a high control on the deposition parameters. This aspect is very attractive for the growth of organic p-n junction in view of improving photovoltaic cells and gas sensors.
Organic Photonic Materials and Devices II, 2000
ABSTRACT
Sensors and Microsystems - Proceedings of the 10th Italian Conference, 2008
... system. 3 Results 3.1 Nana structured Titania Growth and Sensitization with Organic Molecules... more ... system. 3 Results 3.1 Nana structured Titania Growth and Sensitization with Organic Molecules Very interesting results in the synthesis of nanostructured titania have been obtained using cluster beams produced by the PMCS. ...
Philosophical Magazine Part B, 2000
Silicon carbide (SiC) films are grown on Si(111) using as a precursor fullerene seeded in helium ... more Silicon carbide (SiC) films are grown on Si(111) using as a precursor fullerene seeded in helium supersonic beams. The regime of energy and flux distributions, achievable by changing the beam parameters, is well suited to synthesizing SiC films under well ordered conditions, because of better control of the synthesis process and of the C60 dissociative absorption. This is confirmed by
Surface Science, 2006
Recently, supersonic molecular-beam epitaxy (SuMBE) was invented as an alternative method for the... more Recently, supersonic molecular-beam epitaxy (SuMBE) was invented as an alternative method for the deposition of organic material, using higher kinetic energies for deposition than conventional organic molecular-beam epitaxy (OMBE). Using titanyl phthalocyanine (TiOPc) as a model substance, we show that the SuMBE deposition results in increased crystal quality of the deposited material. This is induced by the high kinetic energy
A problem of increasing interest in the last years, both for mass-spectrometry and for deposition... more A problem of increasing interest in the last years, both for mass-spectrometry and for deposition of organic semiconductor films, is to increase and control the flux of large organic molecules seeded in a carrier gas expanding towards a skimmer. This paper deals with experimental and numerical investigations on the dependence of kinetic energy of Pentacene molecules from the gas flow rate. Pentacene is a very important molecule in the field of organic semiconductors where it plays the role of a prototypical system for molecular electronics. The numerical results concerning the flow rate of helium through an optimized capillary as well as the kinetic energy of Pentacene molecules in the beam are in qualitative agreement with the results of measurements paving the way to the optimization of the device.
The flow in conical supersonic micronozzles and behind them by deposition of pentacene accelerate... more The flow in conical supersonic micronozzles and behind them by deposition of pentacene accelerated by helium was studied with the use of direct simulation Monte-Carlo method. The Knudsen number in critical cross-section of nozzles is 0.0043. A directedness of resulting accelerated pentacene flow was studied as a function of cone angle and geometrical Mach number of the nozzle. The intensity of heavy gas flow in the hypersonic region can be elevated by one order using supersonic nozzles.
An approach to the growth of films of π-conjugated organic materials, cluster assembled and nanoh... more An approach to the growth of films of π-conjugated organic materials, cluster assembled and nanohybrid materials combining supersonic free jets with a UHV deposition apparatus including surface characterization methods will be discussed. The unique control achievable with supersonic beams on initial kinetic energy, momentum and state of aggregation enables the growth of materials with controlled properties at different length scales. Results obtained with organic semiconductors and oligomers point out the crucial role of kinetic energy in growing organic crystalline films with well controlled morphologies and structures. By means of supersonic beams of clusters, nanocrystalline metal oxide films can be grown without annealing, so that grain size and morphology can be better controlled. In a co-deposition scheme these interesting features are combined in order to obtain a new class of hybrid functional materials with appealing properties for electronics, gas sensing and photovoltaic applications.
The energy dependences of the rate coefficients for the reactions of CH sub n with O2 and NO were... more The energy dependences of the rate coefficients for the reactions of CH sub n with O2 and NO were investigated with n = 0,1,2. A drift experiment in the energy range from 0.1 to approximately 1 eV was performed. The product distributions as a function of the relative energy between ions and reactants was determined for some of the reactions.
... Tullio Toccoli, Maurizio Ferrari, Sabina Ronchin, Alessandro Podestà1, Paolo Milani1 and Salv... more ... Tullio Toccoli, Maurizio Ferrari, Sabina Ronchin, Alessandro Podestà1, Paolo Milani1 and Salvatore Iannotta CeFSA CNR/ITC Research Center on Aggregates Physics, Via Sommarive 18 38050 ... 9. F. Biasioli, A. Boschetti, E. Barborini, P. Piseri, P. Milani and S. Iannotta, Chem. ...
ABSTRACT A well characterized C60 supersonic seeded beam has been used to synthesize SiC films on... more ABSTRACT A well characterized C60 supersonic seeded beam has been used to synthesize SiC films on Si (111) 7×7. The control of beam parameters such as energy and flux distributions is shown to be important to improve quality of films in terms of morphology, defect density and structure. We demonstrate that a kinetic energy of a few eV of the C60 precursor is enough to induce carbidization at moderate substrate temperature. Kinetic energy activated SiC formation at 750°C is achieved with a strong reduction of the dimensions and density of defects. The films show a reduced roughness of about 2.5 nm (root mean square).
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Papers by Salvatore Iannotta