Technology roadmap for development of SiC sensors at plasma processes laboratory

Recognizing the need to consolidate the research and development (R&D) activities in microelectronics fields in a strategic manner, the Plasma Processes Laboratory of the Technological Institute of Aeronautics (LPP-ITA) has established a technology roadmap to serve as a guide for activities related to development of sensors based on silicon carbide (SiC) thin films. These sensors have also potential interest to the aerospace field due to their ability to operate in harsh environment such as high temperatures and intense radiation. In the present paper, this roadmap is described and presented in four main sections: i) introduction, ii) what we have already done in the past, iii) what we are doing in this moment, and iv) our targets up to 2015. The critical technological issues were evaluated for different categories: SiC deposition techniques, SiC processing techniques for sensors fabrication and sensors characterization. This roadmap also presents a shared vision of how R&D activities in microelectronics should develop over the next five years in our laboratory

Characterization of SiC Thin Films Deposited by HiPIMS

In this work thin films of silicon carbide (SiC) were deposited on silicon wafers by High Power Impulse Magnetron Sputtering (HiPIMS) technique varying the average power of the discharge on a stoichiometric SiC target. X-ray diffraction, Raman spectroscopy, scanning electron microscopy and profilometry were used to analyze the films. It was observed that high values of the average electric power favors the formation of C-C bonds, while low values of the power promote the formation of Si-C bonds. At high power, we have also observed higher deposition rates, but the samples present surface imperfections, causing increase in the roughness and decrease in the film uniformity.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Inst Tecnol Aeronaut ITA, Ctr Tecn Aeroespacial CTA, BR-12228900 Sao Jose Dos Campos, SP, BrazilUniv Vale Paraiba, UNIVAP, BR-12244390 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo, UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo, UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilWeb of Scienc

Degradation of carbon-based materials under ablative conditions produced by a high enthalpy plasma jet

A stationary experiment was performed to study the degradation of carbon-based materials by immersion in a plasma jet. In the experiment, graphite and C/C composite were chosen as the target materials, and the reactive plasma jet was generated by an air plasma torch. For macroscopic study of the material degradation, the sample’s mass losses were measured as function of the exposure time under various temperatures on the sample surface. A microscopic analysis was then carried out for the study of microscopic aspects of the erosion of material surface. These experiments showed that the mass loss per unit area is approximately proportional to the exposure time and strongly depends on the temperature of the material surface. The mass erosion rate of graphite was appreciably higher than the C/C composite. The ablation rate in the carbon matrix region in C/C composite was also noticeably higher than that in the fiber region. In addition, the latter varied according to the orientation of fibers relatively to the flow direction. These tests indicated an excellent ablation resistance of the C/C composite, thus being a reliable material for rocket nozzles and heat shielding elements of the protection systems of hypersonic apparatuses from aerodynamic heating

Sterilization of endodontic files with oxygen plasma

The present paper reports the effectiveness of a new sterilization technique for endodontic files contaminated with Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus in oxygen plasma formed through a continuous electric discharge of 75 mA. The results demonstrated effective elimination of the tested microorganisms, using a process in low temperatures and which requires less time than that established for conventional processes (Pasteur’s oven and autoclave). Gram-positive microorganisms such as Staphylococcus aureus, require more time of plasma bombardment than Gram-negative microorganisms. Files contaminated with Pseudomonas aeruginosa and Escherichia coli were sterilized within a 1-minute exposure, while Staphylococcus aureus required 10 minutes.No presente trabalho, analisou-se a eficácia de uma nova técnica de esterilização de instrumental odontológico. Limas endodônticas contaminadas com Escherichia coli, Pseudomonas aeruginosa e Staphylococcus aureus foram esterilizadas em plasma de oxigênio formado através de uma descarga elétrica contínua de 75 mA. Os resultados demonstraram efetiva eliminação dos microrganismos testados, utilizando-se um processo a baixas temperaturas e em tempos menores que os preconizados para processos convencionais (forno de Pasteur e autoclave). Microrganismos gram-negativos foram destruídos em 1 minuto de exposição e gram-positivos em 10 minutos

AÇÃO ANTIFÚNGICA DE UM JATO DE PLASMA NÃO-TERMICO DE HÉLIO/AR COMPRIMIDO SOBRE BIOFILMES DE CANDIDA ALBICANS

Os biofilmes fúngicos são uma predominante causa de infecções crônicas associadas à utilização de cateteres e próteses, conferindo resistência aos antibióticos e fatores imunológicos do hospedeiro, sendo as leveduras, do gênero Candida spp, as mais frequentemente isoladas. O plasma não-térmico, operado à pressão atmosférica, vem ganhando destaque como uma nova estratégia antimicrobiana, inclusive para erradicação de biofilmes. Este trabalho teve como objetivo avaliar a eficácia da inativação de biofilmes de Candida albicans ATCC sobre substrato de poliuretano, utilizando jatos de plasma atmosférico de 6L/min de hélio e 4L/min de ar comprimido, alternando entre sistema contínuo e pulsado, com frequência de 60Hz e distâncias de 10 a 30mm entre o bocal e substrato. Após tratamento, realizou-se a contagem das unidades formadoras de colônia e a análise morfológica da superfície do biofilme por Microscopia Eletrônica de Varredura. O melhor grupo foi o plasma de modo pulsado com distância de 30mm com redução de 92% das unidades formadoras de colônia, demonstrando ser uma tecnologia promissora para o controle de biofilmes de C. albicans

A historical overview of the research on TiO2 thin films deposited by atomic layer deposition – Part I: Early Studies

<p>Molecular Layering (ML) or Atomic Layer Epitaxy (ALE) or Atomic Layer Deposition (ALD) technique is a gas-phase layer by layer deposition method which belongs to the general class of Chemical Vapor Deposition (CVD) techniques, and which has become of worldwide importance due to success in down-scaling of microelectronic devices. Among the materials obtained by the technique, titanium dioxide (TiO₂) stands out due to its crystallographic importance and numerous applications ranging from the photovoltaics to self-cleaning surfaces. Here we present an overview of the history of TiO₂ thin films grown by ALD technique organized into three periods: early studies (1960s-1990s), consolidation period (2000s) and current stage (2010-present). First, we report the early material synthesis and characterization studies on ALD TiO₂ thin films during the 4 decades between 1960s to 1990s. Then we address the evolution of the research field from the 2000s until the present day. The purpose of this historical survey is to synthetize the evolution of ALD TiO₂ thin films technology for different applications, which could be useful for students and researchers working in this field. In this manuscript, Part I is presented reporting the first published studies on TiO₂ thin films deposited by ALD. </p