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Dive into the research topics where Romina Zonca is active.

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Featured researches published by Romina Zonca.


Applied Physics Letters | 2004

Amorphous-to-crystal transition of nitrogen- and oxygen-doped Ge2Sb2Te5 films studied by in situ resistance measurements

S. Privitera; E. Rimini; Romina Zonca

The amorphous-to-crystal transition has been studied through in situ resistance measurements in Ge2Sb2Te5 thin films doped by ion implantation with nitrogen or oxygen. The dependence of the electrical resistivity and structure on the annealing temperature and time has been investigated in samples with different dopant concentrations. Enhancement of the thermal stability and increase of the mobility gap for conduction have been observed in O- and N-doped amorphous Ge2Sb2Te5. Larger effects have been found in the case of nitrogen doping.


Applied Physics Letters | 2004

Crystal nucleation and growth processes in Ge2Sb2Te5

S. Privitera; Corrado Bongiorno; E. Rimini; Romina Zonca

The kinetics of the amorphous-to-crystal transition in Ge2Sb2Te5 thin films have been studied through in situ transmission electron microscopy analyses. By following the time evolution of the grain density and size, the growth velocity and the nucleation rate have been separately measured at different annealing temperatures. Activation energies of 2.9±0.5 eV and 2.3±0.4 eV have been obtained for the nucleation rate and the growth velocity, respectively. The barrier energy for the nucleation of a critical nucleus ΔG* has been evaluated, and the scalability of phase change nonvolatile memories has been estimated.


Journal of Applied Physics | 2003

Crystallization and phase separation in Ge2+xSb2Te5 thin films

S. Privitera; E. Rimini; C. Bongiorno; Romina Zonca; A. Pirovano; R. Bez

The electrical properties and the structure of isothermally annealed thin films of Ge2+xSb2Te5 (x=0 and 0.5) have been studied by in situ electrical measurements, x-ray diffraction, and transmission electron microscopy analyses. Phase separation has been observed in samples with an excess of Ge; by annealing amorphous Ge2.5Sb2Te5 films at temperatures in the range 130–160 °C, the material cannot be completely converted into the metastable face-centered-cubic (fcc) structure. At temperatures higher than 160 °C, the residual amorphous material may be converted into a fcc structure with a lower lattice parameter.


Journal of Applied Physics | 2000

Effects of nitridation by nitric oxide on the leakage current of thin SiO2 gate oxides

C. Gerardi; M. Melanotte; S. Lombardo; Mauro Alessandri; Barbara Crivelli; Romina Zonca

We have studied the effects of nitridation with nitric oxide on the leakage current of thin (<8 nm) gate oxides. Under gate injection of electrons the oxide leakage current behavior reflects the trend of the electrical thickness and flatband voltage and it can be modeled by the Fowler–Nordheim relation. Conversely, a different behavior is observed for electron injection from the substrate. The leakage current during substrate injection is strictly related to the nitrogen that, as observed by secondary ion mass spectrometry, is located at the SiO2/Si substrate interface.


Journal of Non-crystalline Solids | 2001

The impact of the nitridation process on the properties of the Si–SiO2 interface

Maria Luisa Polignano; Mauro Alessandri; Barbara Crivelli; Romina Zonca; A.P. Caricato; M. Bersani; M. Sbetti; L. Vanzetti

Abstract A newly developed technique for the simultaneous measurement of the oxide–silicon interface properties and of minority carrier lifetime in the silicon volume was used for a systematic study of the nitridation process of oxide films.This technique is based on the surface recombination velocity measurements, and does not require the formation of a capacitor structure, so it is suitable for the measurement of as-grown interface properties. Oxides grown both in dry and in wet environments were prepared, and nitridation processes in N2O and in NO were compared to N2 annealing processes. The effect of nitridation temperature and duration were also studied, and processes of rapid thermal oxidation (RTO) and nitridation (RTN) were compared to conventional furnace nitridation processes. Surface recombination velocity was correlated with nitrogen concentration at the oxide–silicon interface obtained by secondary ion mass spectroscopy (SIMS) measurements. Surface recombination velocity (hence surface state density) decreases with increasing nitrogen pile-up at the oxide–silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are much more effective than N2O treatments in the formation of a nitrogen–rich interface layer and, as a consequence, in interface state reduction. X-ray photoelectron spectrometry (XPS) analyses were used to extend our correlation to very thin oxides (3 nm).


Journal of Non-crystalline Solids | 1999

Surface morphology of nitrided thin thermal SiO2 studied by atomic force microscopy

G. Tallarida; F. Cazzaniga; Barbara Crivelli; Romina Zonca; Mauro Alessandri

In this work the surface morphology of nitrided silicon dioxide is extensively studied using atomic force microscopy. Nitridation is obtained by thermal annealing in nitriding atmosphere in conventional furnace, immediately after thermal oxidation of silicon substrates. The characterisation performed concerns the oxide surface, as well as the region where nitrogen is incorporated, the latter exposed using a diluted HF solution. Significant differences in the morphology of the nitrided layer are observed, which are a function of the nitridation process applied. They allow us to correlate the morphology to the nitrogen incorporation mechanisms that have occurred.


Micron | 2000

Nitridation of gate and tunnel oxides employed in CMOS-ULSI technology

C. Gerardi; M. Melanotte; Barbara Crivelli; Romina Zonca; Mauro Alessandri

Nitridation treatments are very important in CMOS technology because of their capability of improving the gate and tunnel oxide reliability. In this work we report on N2O and NO annealing of pre-oxidised samples showing physical and electrical characteristics of the thin oxides. The difference between the physical behaviours of N2O and NO oxides is evidenced and related to their different electrical properties.


Archive | 2002

Small area contact region, high efficiency phase change memory cell and fabrication method thereof

Roberto Bez; Fabio Pellizzer; Caterina Riva; Romina Zonca


Archive | 2005

Phase change memory cell and manufacturing method thereof using minitrenches

Roberto Bez; Fabio Pellizzer; Marina Tosi; Romina Zonca


Archive | 2002

Minute contact area in semiconductor device, high performance phase change memory cell and method of manufacturing the memory cell

Roberto Bez; Fabio Pellizzer; Caterina Riva; Romina Zonca; カテリーナ・リーヴァ; ファビオ・ペリゼール; ロベルト・ベズ; ロミーナ・ゾンカ

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E. Rimini

University of Catania

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