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Financial communication and CSR: an investigation of italian utilities and financial services disclosure through Twitter from 2016 to 2018
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Electrical and photogalvanic properties of Fe:LiNbO3 thin films fabricated by ion slicing
Get PDFWith the constantly growing global energy demand and the connected deterioration
of the physical environment, great efforts are being devoted to develop renewable and
carbon-free energy sources. The ability of photovoltaic to harvest electric energy from
light makes it one of the promising technologies to help solving the energy problem.
Classical photovoltaic technology, which is based on p-n junctions, could be improved
by the transition to ferroelectric materials that exhibit a bulk photovoltaic effect.
These materials could provide access to higher power conversion efficiencies, thanks
to their higher achievable open-circuit voltages, while the lack of a p-n junction would
make them simpler and cheaper to fabricate. It has been recently proposed that a
way to increase the conversion efficiency of ferroelectric photovoltaic could be through
the use of nano-sized crystals. Focusing our attention on iron doped lithium niobate
as a prototypical material, the proposed experiment involves the fabrication of Fe:LN
heterostructures based on a commercial Fe:LN Smart-Cut(TM) thin film, with junctions
on metal or semiconductor electrodes. The ultimate goal is to investigate how the
current photogeneration behaves at the nano-scale; for this reason, it is mandatory
to understand the physics behind the charge transport processes, the role of the
interfaces and the impact of the ferroelectric switching on the final device. The study
of the electrical and photogalvanic properties is achieved by analysing current-voltage
characteristic curves measured with a source meter both in dark and lit conditions.
The analysis of dark I-V curves shows that Richardson-Schottky and Poole-Frenkel
models are the most appropriate ones to describe the charge transport in our samples,
as expected from considering their band diagrams. Then, the particular current peaks
observed in the case of PEDOT:PSS electrodes are attributed to the polarization
switching of the crystalline film. Their characterization provides an estimation of
the main related quantities, such as the spontaneous polarization and the coercive
and residual fields, which are compared successfully with results from other works
reported in literature. Finally, the measured photogalvanic currents are studied in
relation to the illumination irradiance, producing results in line with those present
in literature
Optical non-classicality as a Quantum Resource in Continuous-Variable Quantum Information
Get PDFIn this thesis we address the problem of building a Quantum Resource Theory in infinite dimension. In particular, we study bosonic non-classicality as a Quantum Resource in continuous-variable Quantum Information. After reviewing the formalism of open quantum systems and Quantum Optics, we introduce the framework of Quantum Resource Theories and we discuss the case of non-classicality, and its applications in Quantum Optics and Quantum Technologies. Finally, we study a Resource Theory of non-classicality based on the standard and measured relative entropies of non-classicality as resource monotones and we prove, for the first time in an infinite-dimensional Resource Theory, a bound for asymptotic conversion rates
Study of the 20Ne(p,gamma)21Na reaction at astrophysical energies
Get PDFThe 20Ne(p,gamma)21Na is the first reaction of the NeNa cycle and having the slowest reaction rate it controls the speed of the entire cycle. The rate of the 20Ne(p,gamma)21Na reaction, depending on the temperature, is dominated by the high energy tail of a sub-threshold state at E_R = -6.7 keV, a direct capture component and a narrow resonance at E_R = 366 keV. In the next months LUNA at Laboratori Nazionali del Gran Sasso, will study the resonance and measure the cross section below 400 keV. The experimental approach and the study of the reaction using Monte Carlo simulation will be presented
