Thermal evaporation furnace with improved configuration for growing nanostructured inorganic materials

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A tubular furnace specifically designed for growing nanostructured materials is presented in this work. The configuration allows an accurate control of evaporation temperature, substrate temperature, total pressure, oxygen partial pressure, volumetric flow and source-substrate distance, with the possibility of performing both downstream and upstream depositions. In order to illustrate the versatility of the equipment, the furnace was used for growing semiconducting oxide nanostructures under different deposition conditions. Highly crystalline indium oxide nanowires with different morphologies were synthesized by evaporating mixtures of indium oxide and graphite powders with different mass ratios at temperatures between 900 degrees C and 1050 degrees C. The nanostructured layers were deposited onto oxidized silicon substrates with patterned gold catalyst in the temperature range from 600 degrees C to 900 degrees C. Gas sensors based on these nanowires exhibited enhanced sensitivity towards oxygen, with good response and recovery times. (C) 2011 American Institute of Physics. [doi:10.1063/1.3597577]826Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [DD05/59270-0

Influence of ambient gas on the growth and properties of porous tin-doped indium oxide thin films made by pulsed laser deposition

The laser ablation method was used for depositing porous nanocrystalline indium-tin oxide thin films for gas sensing applications. Samples were prepared at different pressures using three gases (O-2, 0.8N(2):0.2O(2), N-2) and heat-treated in the same atmosphere used for the ablation process. X-ray diffraction results show that the films are not oriented and the grain sizes are in the range between 15 and 40 nm. The grains are round shaped for all samples and the porosity of the films increases with the deposition pressure. The degree of sintering after heat treatment increases for lower oxygen concentrations, generating fractures on the surface of the samples. Film thicknesses are in the range of I pm for all gases as determined from scanning electron microscopy cross-sections. Electrical resistance varies between 36.3 ohm for the film made at 10 Pa pressure in N-2 until 9.35 x 10(7) ohm for the film made at 100 Pa in O-2. (C) 2007 Elsevier B.V. All rights reserved

Fabrication Of Molds For Pdms Microfluidic Devices By Laser Swelling Of Pmma

The volume increase experienced by Polymethylmethacrylate (PMMA), a common thermoplastic material, when subjected to a fast heating-cooling cycle by the action of an ultraviolet laser beam has been investigated in this work. The effects of laser power, focusing, writing speed, cooling and number of exposures on the dimensions of ridges formed by surface swelling were quantified. The biggest swellings, having near Gaussian cross-sectional shapes, were obtained by performing laser treatments with the polymer immersed in water. The laser swelling technique was applied to the fabrication of molds for microfluidic chips made from Polydimethylsiloxane (PDMS) and the results of the study are discussed within this framework. The method allows the rapid fabrication of molds with a very smooth finish, providing dimensional accuracy appropriate for replication of complex PDMS microfluidic devices. This journal is5322508925096Squires, T.M., Quake, S.R., (2005) Rev. Mod. Phys., 77, pp. 977-1026Stone, H.A., Stroock, A.D., Ajdari, A., (2004) Annu. Rev. Fluid Mech., 36, pp. 381-411Erickson, D., Li, D.Q., (2004) Anal. Chim. Acta, 507, pp. 11-26Duffy, D.C., McDonald, J.C., Schueller, O.J.A., Whitesides, G.M., (1998) Anal. Chem., 70, pp. 4974-4984McDonald, J.C., Whitesides, G.M., (2002) Acc. Chem. Res., 35, pp. 491-499Fujii, T., (2002) Microelectron. Eng., 61 (2), pp. 907-914Nieto, D., Delgado, T., Flores-Arias, M.T., (2014) Opt. Laser Eng., 63, pp. 11-18Micheal, I.J., Vidyasagar, A.J., Bokara, K.K., Mekala, N.K., Asthana, A., Rao, C.M., (2014) Lab Chip, 14, pp. 3695-3699McDonald, J.C., Chabinyc, M.L., Metallo, S.J., Anderson, J.R., Stroock, A.D., Whitesides, G.M., (2002) Anal. Chem., 74, pp. 1537-1545Becker, H., Locascio, L.E., (2002) Talanta, 56, pp. 267-287Becker, H., Gartner, C., (2000) Electrophoresis, 21, pp. 12-26Chung, C.K., Lin, Y.C., Huang, G.R., (2005) J. Micromech. Microeng., 15, pp. 1878-1884Teixidor, D., Orozco, F., Thepsonthi, T., Ciurana, J., Rodriguez, C.A., Oezel, T., (2013) Int. J. Adv. Des. Manuf. Technol., 67, pp. 1651-1664Romoli, L., Tantussi, G., Dini, G., (2011) Opt. Laser Eng., 49, pp. 419-427Wang, Z.K., Zheng, H.Y., Lim, R.Y.H., Wang, Z.F., Lam, Y.C., (2011) J. Micromech. Microeng., 21, p. 095008Teixidor, D., Thepsonthi, T., Ciurana, J., Özel, T., (2012) J. Manuf. Process., 14, pp. 435-442Beinhorn, F., Ihlemann, J., Luther, K., Troe, J., (1999) Appl. Phys. A: Mater. Sci. Process., 68, pp. 709-713Meunier, T., Villafranca, A.B., Bhardwaj, R., Weck, A., (2012) Opt. Lett., 37, pp. 4266-4268Li, H., Fan, Y., Conchouso, D., Foulds, I.G., (2012) J. Micromech. Microeng., 22, p. 115037Himmelbauer, M., Arenholz, E., Bauerle, D., Schilcher, K., (1996) Appl. Phys. A: Mater. Sci. Process., 63, pp. 337-339Masubuchi, T., Furutani, H., Fukumura, H., Masuhara, H., (2001) J. Phys. Chem. B, 105, pp. 2518-2524Malyshev, A.Y., Bityurin, N.M., (2005) Quantum Electron., 35, pp. 825-830Bityurin, N., (2009) Appl. Surf. Sci., 255, pp. 9851-9855Malyshev, A.Y., Agareva, N.A., Mal'Shakova, O.A., Bityurin, N.M., (2007) J. Opt. Technol., 74, pp. 641-646Bityurin, N.M., (2010) Quantum Electron., 40, pp. 955-965Ru, E.L., Etchegoin, P., (2009) Principles of Surface Enhanced Raman Spectroscopy and Related Plasmonic Effects, , Elsevier, AmsterdamWochnowski, C., Eldin, M.A.S., Metev, S., (2005) Polym. Degrad. Stab., 89, pp. 252-264Rebollar, E., Bounos, G., Oujja, M., Georgiou, S., Castillejo, M., (2007) Appl. Surf. Sci., 253, pp. 7820-782

Resistive-Switching Behavior in Polycrystalline CaCu3Ti4O12 Nanorods

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Highly aligned CaCu3Ti4O12 nanorod arrays were grown on Si/SiO2/Ti/Pt substrates by radio-frequency sputtering at a low deposition temperature of 300 degrees C and room temperature. Structural and morphological studies have shown that the nanostructures have a polycrystalline nature and are oriented perpendicular to the substrate. The high density of grain boundaries in the nanorods is responsible for the nonlinear current behavior observed in these arrays. The current-voltage (I-V) characteristics observed in nanorods were attributed to the resistive memory phenomenon. The electrical resistance of microcapacitors composed of CaCu3Ti4O12 nanorods could be reversibly switched between two stable resistance states by varying the applied electric field. In order to explain this switching mechanism, a model based on the increase/decrease of electrical conduction controlled by grain boundary polarization has been proposed.32500504Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)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)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPESP [PD 2006/61758-4

Resistive-switching Behavior In Polycrystalline Cacu 3ti 4o 12 Nanorods

Highly aligned CaCu 3Ti 4O 12 nanorod arrays were grown on Si/SiO 2/Ti/Pt substrates by radio-frequency sputtering at a low deposition temperature of 300 °C and room temperature. Structural and morphological studies have shown that the nanostructures have a polycrystalline nature and are oriented perpendicular to the substrate. The high density of grain boundaries in the nanorods is responsible for the nonlinear current behavior observed in these arrays. The currentvoltage (I-V) characteristics observed in nanorods were attributed to the resistive memory phenomenon. The electrical resistance of microcapacitors composed of CaCu 3Ti 4O 12 nanorods could be reversibly switched between two stable resistance states by varying the applied electric field. In order to explain this switching mechanism, a model based on the increase/decrease of electrical conduction controlled by grain boundary polarization has been proposed. © 2011 American Chemical Society.32500504Homes, C.C., Vogt, T., Shapiro, S.M., Wakimoto, S., Ramirez, A.P., (2001) Science, 293, p. 673Subramanian, M.A., Li, D., Duan, N., Reisner, B.A., Sleight, A.W., (2000) J. Solid State Chem., 151, p. 323Ramirez, A.P., Subramanian, M.A., Gardel, M., Blumberg, G., Li, D., Vogt, T., Shapiro, S.M., (2000) Solid State Commun., 115, p. 217Chung, S.Y., Kim, I.D., Kang, S.J.L., (2004) Nat. Mater., 3, p. 774Sinclair, D.C., Adams, T.B., Morrison, F.D., West, A.R., (2002) Appl. Phys. Lett., 80, p. 2153Joanni, E., Savu, R., Bueno, P.R., Longo, E., Varela, J.A., (2008) Appl. Phys. Lett., 92, p. 132110Parra, R., Joanni, E., Espinosa, J.W.M., Tararam, R., Cilense, M., Bueno, P.R., Varela, J.A., Longo, E., (2008) J. Am. Ceram. Soc., 91, p. 4162Shen, Y.S., Chiou, B.S., Ho, C.C., (2008) Thin Solid Films, 517, p. 1209Lo Nigro, R., Toro, R.G., Malandrino, G., Fragala, I.L., Losurdo, M., Giangregorio, M.M., Bruno, G., Fiorenza, P., (2006) J. Phys. Chem. B, 110, p. 17460Chang, L.C., Lee, D.Y., Ho, C.C., Chiou, B.S., (2007) Thin Solid Films, 516, p. 454Deng, G., Xanthopoulos, N., Muralt, P., (2008) Appl. Phys. Lett., 92, p. 172909Prakash, B.S., Varma, K.B.R., Michau, D., Maglione, M., (2008) Thin Solid Films, 516, p. 2874Wang, N., Cai, Y., Zhang, R.Q., (2008) Mater. Sci. Eng. R, 60, p. 1Xia, Y.N., Yang, P.D., Sun, Y.G., Wu, Y.Y., Mayers, B., Gates, B., Yin, Y.D., Yan, Y.Q., (2003) Adv. Mater., 15, p. 353Joanni, E., Savu, R., Jancar, B., Bueno, P.R., Varela, J.A., (2010) J. Am. Ceram. Soc., 93, p. 51Lin, C.C., Lin, C.Y., Lin, M.H., Lin, C.H., Tseng, T.Y., (2007) IEEE Trans. Electron Devices, 54, p. 3146Guan, W.H., Long, S.B., Liu, Q., Liu, M., Wang, W., (2008) IEEE Electron Device Lett., 29, p. 434Schroeder, H., Jeong, D.S., (2007) Microelectron. Eng., 84, p. 1982Park, J.W., Park, J.W., Kim, D.Y., Lee, J.K., (2005) J. Vac. Sci. Technol. A, 23, p. 1309Waser, R., (2009) Microelectron. Eng., 86, p. 1925Shi, J.P., Zhao, Y.G., Zhang, H.J., Tian, H.F., Zhang, X.P., (2009) Appl. Phys. Lett., 94, p. 192103Yang, J.J., Pickett, M.D., Li, X.M., Ohlberg, D.A.A., Stewart, D.R., Williams, R.S., (2008) Nat. Nanotechnol., 3, p. 429Szot, K., Speier, W., Bihlmayer, G., Waser, R., (2006) Nat. Mater., 5, p. 312Choi, B.J., Jeong, D.S., Kim, S.K., Rohde, C., Choi, S., Oh, J.H., Kim, H.J., Tiedke, S., (2005) J. Appl. Phys., 98, p. 033715Seo, S., Lee, M.J., Seo, D.H., Jeoung, E.J., Suh, D.S., Joung, Y.S., Yoo, I.K., Park, B.H., (2004) Appl. Phys. Lett., 85, p. 5655Sawa, A., Fujii, T., Kawasaki, M., Tokura, Y., (2004) Appl. Phys. Lett., 85, p. 4073Baikalov, A., Wang, Y.Q., Shen, B., Lorenz, B., Tsui, S., Sun, Y.Y., Xue, Y.Y., Chu, C.W., (2003) Appl. Phys. Lett., 83, p. 957Bueno, P.R., Tararam, R., Parra, R., Joanni, E., Ramirez, M.A., Ribeiro, W.C., Longo, E., Varela, J.A., (2009) J. Phys. D: Appl. Phys., 42, p. 055404Cordeiro, M.A.L., Souza, F.L., Leite, E.R., Lanfredi, A.J.C., (2008) Appl. Phys. Lett., 93, p. 182912Hwang, I., Choi, J., Hong, S., Kim, J.S., Byun, I.S., Bahng, J.H., Koo, J.Y., Park, B.H., (2010) Appl. Phys. Lett., 96, p. 053112Rozenberg, M.J., Inoue, I.H., Sanchez, M.J., (2004) Phys. Rev. Lett., 92, p. 178302Marques, V.P.B., Bueno, P.R., Simoes, A.Z., Cilense, M., Varela, J.A., Longo, E., Leite, E.R., (2006) Solid State Commun., 138, p. 1Kim, I.D., Rothschild, A., Tuller, H.L., (2006) Appl. Phys. Lett., 88, p. 072902Zang, G.Z., Zhang, J.L., Zheng, P., Wang, J.F., Wang, C.L., (2005) J. Phys. D: Appl. Phys., 38, p. 1824Mahan, G.D., (1984) J. Appl. Phys., 55, p. 98

Conductivity in SnO2 polycrystalline thick film gas sensors: Tunneling electron transport and oxygen diffusion

Conduction mechanisms in polycrystalline SnO2 thick sensing films were investigated by means of DC electrical resistance during heating?cooling cycles. Samples were maintained at relatively high temper- atures in H2 or O2 ambient atmospheres before performing electrical measurements under vacuum or before performing XPS measurements in order to determine band bending. Results suggest that inter- grains present Schottky barriers that are responsible for the observed conductivities regardless of gas pre-treatment. Oxygen diffusion modulates barrier widths affecting conductivity through tunneling transport. The electrical response to subsequent exposure to an oxygen atmosphere is consistent with our interpretation.Fil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Schipani, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Ponce, Miguel Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Joanni, E.. CTI Renato Archer; BrasilFil: Williams, Federico Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de Los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentin

Comparasion between TiO2 thin films deposited by DC and RF sputtering

This paper compares titanium oxide (TiO2) thin films deposited by RF and DC sputtering. Structural characterization was used to investigate the morphology of TiO2 thin films. Both films show the rutile and anatase crystal structure; ellipsometry show thickness and refractive index of 50 nm and 2.43 for the TiO2 deposited by DC sputtering and 40 nm and 2.32 for the film by RF sputtering; AFM shows the roots mean square (RMS) roughness of 6.5 nm and 8 nm for TiO2 deposited by DC and RF sputtering, respectively. For electrical characterization was developed MOS capacitor; from them was possible to determine which method forms the best dielectric film, defined by high dielectric constant value (high-k), lower charge density (Q0/q) and flat-band voltage (VFB) around-0.9V. Therefore, the best method to deposit TiO2 is DC reactive sputtering; because this method showed a better electrical conditions and a well-defined crystalline structure.CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESSem informaçãoSem informação34. Symposium on Microelectronics Technology and Device

Pulsed laser deposition of barium metaplumbate thin films for ferroelectric capacitors

Barium metaplumbate thin films were deposited in situ by pulsed laser deposition on Si/SiO2/Ti/Pt substrates with a high deposition rate. The temperatures used ranged between 400 °C and 700 °C. As the deposition temperature was increased, the films assumed a strong (222) preferential orientation. This orientation of the electrodes was reflected on the PZT films, having a very big influence on their ferroelectric behavior. The PZT films made over BPO deposited at high temperature presented high values of remanent polarization (43 μC/cm2) but indications of high leakage currents could be observed in the hysteresis loops. By using BPO bottom electrodes, a 30% improvement in the fatigue behavior of PZT capacitors when compared with the normal platinum electrodes was observed