Nuova ricerca

RICCARDO MAGRIN MAFFEI

Home | Curriculum(pdf) |


Pubblicazioni

2023 - Suppression of grain boundary contributions on carrier mobility in thin Al-doped ZnO epitaxial films [Articolo su rivista]
Magrin Maffei, Riccardo; di Bona, Alessandro; Sygletou, Maria; Bisio, Francesco; D'Addato, Sergio; Benedetti, Stefania
abstract

2023 - Thermoelectric and Structural Properties of Sputtered AZO Thin Films with Varying Al Doping Ratios [Articolo su rivista]
Isram, Muhammad; MAGRIN MAFFEI, Riccardo; Demontis, Valeria; Martini, Leonardo; Forti, Stiven; Coletti, Camilla; Bellani, Vittorio; Mescola, Andrea; Paolicelli, Guido; Rota, Alberto; Benedetti, Stefania; DI BONA, Alessandro; Ribeiro, Joana M.; Tavares, C. J.; Rossella, Francesco
abstract

2023 - Unveiling the Thermoelectric Performances of Zn1−xFexSe Nanoparticles Prepared by the Hydrothermal Method [Articolo su rivista]
Isram, Muhammad; Demontis, Valeria; Magrin Maffei, Riccardo; Abbas Khan, Najaf; di Bona, Alessandro; Benedetti, Stefania; Amin, Nasir; Mahmood, Khalid; Rossella, Francesco
abstract

Fe2+-doped ZnSe nanoparticles, with varying concentrations of Fe2+ dopants, were prepared by the hydrothermal method and investigated using a multi-technique approach exploiting scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy, as well as measurement of the electrical transport properties and Seebeck coefficient (S). The doped nanoparticles appeared as variable-sized agglomerates on nanocrystallites upon SEM investigation for any doping level. Combined XRD and Raman analyses revealed the occurrence of a cubic structure in the investigated samples. Electric and thermoelectric (TE) transport investigations showed an increase in TE performance with an increase in Fe atom concentrations, which resulted in an enhancement of the power factors from 13 µWm−1K−2 to 120 µWm−1K−2 at room temperature. The results were also dependent on the operating temperature. The maximum power factor of 9 × 10−3 Wm−1K−2 was achieved at 150 °C for the highest explored doping value. The possible applications of these findings were discussed.

2022 - Forward emission of positronium from nanochanneled silicon membranes [Articolo su rivista]
Mariazzi, S.; Rienacker, B.; Magrin Maffei, R.; Povolo, L.; Sharma, S.; Caravita, R.; Penasa, L.; Bettotti, P.; Doser, M.; Brusa, R. S.
abstract

Positronium beam formation and manipulation are required in several fundamental experiments. Efficient positron/positronium conversion in transmission configuration would offer important geometrical advantages over the reflection one for these applications. A novel type of transmission positron/positronium converters, which consists of silicon membranes with pass-through nanochannels, was produced and tested. The amount of forward emitted positronium was studied as a function of the thickness of the membranes and the nanochannel size. A maximum of, at least, (16±4)% of positrons implanted in (3.5±0.5)-μm-thick membrane with a nanochannel size of 5-8 nm were found to be forward emitted as positronium. A similar maximum amount of, at least, (16±5)%, was found to be emitted from a membrane (7.7±1.3)-μm-thick with a nanochannel size of 7-10 nm. A preliminary evaluation shows that the maximum amount of forward emitted positronium with the entire kinetic energy distribution below 1 eV is, at least, 9% of the positrons implanted in the (3.5±0.5)-μm-thick membrane.

2021 - Zno thin films growth optimization for piezoelectric application [Articolo su rivista]
Polewczyk, V.; Magrin Maffei, R.; Vinai, G.; Lo Cicero, M.; Prato, S.; Capaldo, P.; Dal Zilio, S.; Di Bona, A.; Paolicelli, G.; Mescola, A.; D'addato, S.; Torelli, P.; Benedetti, S.
abstract

The piezoelectric response of ZnO thin films in heterostructure-based devices is strictly related to their structure and morphology. We optimize the fabrication of piezoelectric ZnO to reduce its surface roughness, improving the crystalline quality, taking into consideration the role of the metal electrode underneath. The role of thermal treatments, as well as sputtering gas composition, is investigated by means of atomic force microscopy and x-ray diffraction. The results show an optimal reduction in surface roughness and at the same time a good crystalline quality when 75% O2 is introduced in the sputtering gas and deposition is performed between room temperature and 573 K. Subsequent annealing at 773 K further improves the film quality. The introduction of Ti or Pt as bottom electrode maintains a good surface and crystalline quality. By means of piezoelectric force microscope, we prove a piezoelectric response of the film in accordance with the literature, in spite of the low ZnO thickness and the reduced grain size, with a unipolar orientation and homogenous displacement when deposited on Ti electrode.