Archivio della ricerca - Fondazione Bruno Kessler
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Material Characterization of 4H-SiC - Influence of Protection Layer Thickness on Dopant Depth During Ion-Implantation
No full textThe overall goal of the present research is to understand the behaviour of dopants in 4H-SiC (4H-
Silicon Carbide).
4H-Silicon Carbide (4H-SiC) is renowned for its high thermal stability, wide bandgap, and suitability for high-power and high-temperature electronic applications. [1–2] This study focuses on analyzing the distribution and diffusion behaviour of dopants in 4H-SiC, as well as the resulting surface modifications, following aluminum (Al) ion implantation and subsequent post-implantation annealing. Based on our selected implantation parameters (dose, energy, and temperature) and post-annealing conditions (temperature and time), Dynamic Secondary Ion Mass Spectrometry (SIMS) measurements are being conducted to acquire quantitative depth profiles of the implanted aluminum. These measurements enable a detailed assessment of the aluminum distribution, including the identification of diffusion tails and potential segregation effects, under our specific processing conditions. Comparative analysis of the profiles before and after thermal annealing provides critical insights into dopant activation behaviour, redistribution mechanisms, and the influence of annealing on the stability of the dopant profile. In parallel, TOF-SIMS is used to investigate surface effects such as dopant clustering, and contamination because high-temperature annealing can cause sublimation of silicon, resulting in a carbon-rich surface layer that may lead to carbon agglomeration. In addition, Al dopant may accumulate near the surface at high-temperature, and the presence of trace oxygen or moisture may result in surface oxidation.
TOF-SIMS plays a crucial role in identifying these surface changes by enabling high-sensitivity
detection of carbon build-up, residual aluminum, oxygen, and other contaminants. This enhances our understanding of post-annealing surface chemistry in Al-implanted 4H-SiC.
Using both SIMS methods gives a clear picture of how dopants behave in SiC and helps improve
doping processes. This highlights SIMS as a key tool for refining implantation and annealing steps in 4H-SiC devices
Role-Play Large Language Models for Short Behavior Change Interventions: An Exploratory Study on Brief Action Planning
No full textThis study explores the feasibility of using Large Language Models for delivering structured behavior change interventions, focusing on Brief Action Planning for sedentary lifestyles. We leveraged a zero-shot prompting strategy without fine-tuning or providing specific data to the model. In particular, we used role-play prompting to develop an intelligent agent guided by motivational interviewing principles to support goal-setting and action-planning. The agent’s performance was evaluated through simulations and user studies, assessing its adherence to Brief Action Planning protocols. Results indicate that while role-prompting Large Language Models is a promising approach to scale up time-intensive health interventions, further research is needed to mitigate notable limitations
Anticiper le début de la formation d’un clergé africain ? Les histoires emblématiques des pères Jean-Pierre Moussa (1815-1860) et Daniele Sorur Pharim Den (1860env-1900)
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Effectiveness of eHealth literacy interventions: a systematic review and meta-analysis of experimental studies
No full textBackground: eHealth Literacy (eHL) is a set of competencies and skills encompassing the knowledge, comfort and perceived ability to identify, evaluate and apply electronic health information to health problems. Given its role in the appropriate use of health technologies, ensuring equitable access to health information and improving patient outcomes, this study aims to systematically retrieve, qualitatively and quantitative pool and critically appraise available experimental evidence on the effectiveness of eHL interventions across different population groups. Methods: Following the PRISMA guidelines, we conducted a systematic review in PubMed/Medline, Scopus, Web of Science, Embase, Cochrane Library and ClinicalTrials.gov, including original experimental studies quantifying the effectiveness of interventions aimed at increasing eHL, as assessed by the eHealth Literacy Scale (eHEALS) or other validated scales. We performed a random-effects model meta-analysis comparing changes in eHL levels before and after the interventions, and between the intervention and control groups. Heterogeneity was assessed using I2 statistics. Results: Out of the 504 studies retrieved, 15 studies conducted between 2011 and 2023 met the inclusion criteria. Target populations of eHL interventions included adults in 7 studies, older people in 5 and young people in 4. The meta-analysis included 10 studies that used the eHEALS. Participants showed a mean increase in eHEALS scores of 5.81 points (95% CI = 3.36-8.26, N = 1025) following the eHL interventions compared to the pre-intervention period. In the analysis between the intervention and control groups, we found a statistically significant difference in eHL improvement in favour of the intervention group, with mean eHEALS scores 3.62 points (95% CI = 1.63-5.60, N = 1258) higher in the intervention group than in the control groups. Subgroup analyses by intervention type, stratified by Collaborative Learning (CL) or Individualistic Learning (IL) showed significant increases in eHealth Literacy in the pre-post intervention analysis (CL: UMD = 5.19, CI = 0.01-10.38, N = 402; IL: UMD = 6.05; CI = 3.14-8.97, N = 623) and in the intervention vs. control analysis in the IL group (DMD = 4.98; CI = 1.77-8.12, N = 540). Conclusions: Our findings support the effectiveness of tailored interventions in significantly enhancing eHL, providing key insights for evidence-based intervention design targeted to different population groups
The phenomenon of abortion in foreign women living in Northern Italy: a retrospective cohort epidemiological study
No full textSegmented SiPM Readout for Cherenkov Time-of-Flight Positron Emission Tomography Detectors Based on Bismuth Germanate
No full textPositron emission tomography (PET) is the most sensitive biomedical imaging modality for noninvasively detecting and visualizing positron-emitting radiopharmaceuticals within a subject. In PET, measuring the time-of-flight (TOF) information for each pair of 511 keV annihilation photons improves effective sensitivity but requires high timing resolution. Hybrid materials that emit both scintillation and Cherenkov photons, such as bismuth germanate, recently offer the potential for more precise timing information from Cherenkov photons while maintaining adequate energy resolution from scintillation photons. However, a significant challenge in using such hybrid materials for TOF PET applications lies in the event-dependent timing spread caused by the mixed detection of Cherenkov and scintillation photons due to relatively lower production of Cherenkov photons. This study introduces an innovative approach by segmenting silicon photomultiplier (SiPM) pixels coupled to a single crystal, rather than using traditional SiPMs that are as large as or larger than the crystals they read. We demonstrated that multiple timestamps and photon counts obtained from the segmented SiPM can classify events by providing temporal photon density, effectively addressing this challenge. The approach and findings would lead to new opportunities in applications that require precise timing and photon counting
Levitated Ferromagnetic Magnetometer with Energy Resolution Well Below ħ
No full textA quantum limit on the measurement of magnetic fields has been recently pointed out, stating that the so-called energy resolution ER is bounded to ER≳ħ. This limit indeed holds true for the vast majority of existing quantum magnetometers, including superconducting quantum interference devices and solid state spin and optically pumped atomic magnetometers. However, it can be surpassed by highly correlated spin systems, as recently demonstrated with a single-domain spinor BEC. Here, we show that similar and potentially much better resolution can be achieved with a hard ferromagnet levitated above a superconductor at cryogenic temperature. We demonstrate ER=(0.064±0.010) ħ and anticipate that ER<10−3 ħ is within reach with near-future improvements. This finding opens the way to new applications in condensed matter, biophysics, and fundamental science. In particular, we propose an experiment to search for axionlike dark matter and project a sensitivity that is orders of magnitude better than in previous searches
Integration of germanium-vacancy single photon emitters arrays in diamond nanopillars
Get PDFThe nanoscale fabrication of μm-spaced single-photon emitter arrays is crucial for the development of integrated photonic chips. We report on the fabrication and systematic characterization of germanium-vacancy (GeV) color centers arrays in diamond obtained upon ion implantation at the nanoscale. Ge2+ ion implantations at 35 keV and 70 keV energies were carried out using a focused ion beam (FIB) equipped with a liquid metal alloy ion source. The arrays of emitters are subsequently aligned to ø300 nm nanopillar waveguiding structures, fabricated using a combination of electron-beam lithography and plasma etching. The photon collection efficiency and photoluminescence (PL) signal-to-background ratio increased by a factor 8 with respect to the unstructured sample. The photophysical properties of the GeV emitters fabricated by this approach were unaltered with respect to those found in unprocessed diamond. The efficiency of the overall manufacturing process to fabricate individual GeV centers was assessed. Up to 33% of the fabricated nanopillars, depending on ion implantation parameters, were found to contain single emitters