Comparative study between wet and dry etching of silicon for microchannels fabrication

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOIn this work we present a comparative study of two processes for the fabrication of an array of microchannels for microfluidics applications, based on integrated-circuit technology process steps, such as lithography and dry etching. Two different methods were investigated in order to study the resulting microstructures: wet and dry deep etching of silicon substrate. The typical etching depth necessary to the target application is 50 mu m.1093015FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2016/09509-112. Conference on Advanced Fabrication Technologies for Micro/Nano Optics and Photonics3 a 5 de Fevereiro de 2019San Francisco, CA, Estados UnidosSPIE; Nanoscribe Gmb

Phylogenomics and the rise of the angiosperms

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods1,2. A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome3,4. Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins5,6,7. However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes8. This 15-fold increase in genus-level sampling relative to comparable nuclear studies9 provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade

Study of indium nitride and indium oxynitride band gaps

This work shows the study of the optical band gap of indium oxynitride (InNO) and indium nitride (InN) deposited by magnetron reactive sputtering. InNO shows multi-functionality in electrical and photonic applications, transparency in visible range, wide band gap, high resistivity and low leakage current. The deposition processes were performed in a magnetron sputtering system using a four-inches pure In (99.999%) target and nitrogen and oxygen as plasma gases. The pressure was kept constant at 1.33 Pa and the RF power (13.56 MHz) constant at 250 W. Three-inches diameter silicon wafer with 370 micrometer thickness and resistivity in the range of 10 ohm-centimeter was used as substrate. The thin films were analyzed by UV-Vis-NIR reflectance, photoluminescence (PL) and Hall Effect. The band gap was obtained from Tauc analysis of the reflectance spectra and photoluminescence. The band gap was evaluated for both films: for InNO the value was 2.48 eV and for InN, 1.52 eV. The relative quantities obtained from RBS spectra analysis in InNO sample are 48% O, 12% N, 40% In and in InN sample are 8% O, 65% N, 27% In

Study and characterization of indium oxynitride photoconductors

Multifunctional materials are a new class of thin films and coatings. These materials show interesting characteristics for application in many scientific areas, in special electronic and photonic technologies. These characteristics include sensitivity for thermal, light, mechanical, chemical and other influences, high resistivity, high electrical isolation and transparence in visible range. Recently it was obtained a new oxide type that combines oxygen, nitrogen and indium: the indium oxynitride. In this work, we study the deposition of indium oxynitride by reactive sputtering for application in photoconductor sensors. The deposition processes were performed in a home build magnetron sputtering system, using a four-inch pure In target, nitrogen and oxygen as process gases. The pressure was kept constant at 10 mtorr and the RF power (13.56 MHz) was constant at 250 W. The photoconductors were made with these thin films. The photoelectric detectors were analyzed by IxV (current versus voltage) analyses. The IxV analysis presented a low leakage current (10-8 A). The photoelectric effect was observed from the difference between the case with emitted light and dark currents. It increased around 140 times, under illumination of a halogen lamp. The Hall Effect measurements indicated that the films were n-type semiconductors. The increase in the oxygen concentration added in the plasma, promoted the change in the character of these thin films from conductor to semiconductor material