ANDRE FERREIRA SILVA
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Artigo IPEN-doc 25742 Boron film laser deposition by ultrashort pulses for use as neutron converter material2019 - COSTA, PRISCILA; RAELE, MARCUS P.; MACHADO, NOE G.P.; SILVA, ANDRE F.; VIEIRA JUNIOR, NILSON D.; GENEZINI, FREDERICO A.; SAMAD, RICARDO E.This study investigated the production of boron films by femtosecond pulsed laser deposition (PLD) to be used as converters on bulk semiconductor neutron detectors. The ablation threshold of metallic boron was determined and the film growth was studied as a function of deposition time (5–90 min) and laser pulse energy (35–530 μJ). The films were characterized by scanning electron microscopy (SEM), revealing a flaky morphology, optical profilometry, which determined the films thicknesses (from 80 nm up to 4 μm), Ion Beam Analysis (IBA) that assessed their elemental composition and X-ray diffraction (XRD), which revealed an amorphous structure. In addition, a thermal load study was performed to evaluate the heat flux onto the substrate during deposition process. Stable boron films obtained show that the femtosecond PLD process is reliable and reproducible for the fabrication of thick boron coatings.Resumo IPEN-doc 25015 Analysis of temperature on microscope slide by a boron pulsed laser deposition process2018 - SILVA, ANDRE F.; COSTA, PRISCILA; MACHADO, NOE G.P.; SAMAD, RICARDO E.; ZEZELL, DENISE M.; RAELE, MARCUS P.; ZAMATARO, CLAUDIA B.A boron thin ¯lm can be used for neutrons conversion and in electrically charged particles and further detection. Since boron has a high evaporation temperature and the thickness of the boron layer needs to have few microns, pulsed laser deposition also known as PLD can be used. When producing thin ¯lms with the PLD technique, the target absorbs energy promoting the material ablation creating a plasma plume that deposits material on a substrate, thus creating a thin ¯lm. Since all the deposition occurs in a vacuum chamber, the residual heat of the plasma that condensate at the substrate can build up, thus potentially source of concern if the substrate sensitive to temperature somehow. This work reports the analysis of the variation of temperature in a microscope slide (substrate) as a function of the energy of femtosecond laser pulses. For measuring the substrate temperature a type-K thermocouple was used together with associated electronics. The thermocouple was ¯xed to the back of substrate with thermal grease for vacuum and connected to the microchip using a feed through in the vacuum chamber. Was detected the increase of the substrate+¯lm starting at 6oC from initial temperature (room) for the minimal laser energy 100 microjoules (25 femtoseconds).