The Surface Texturing of Monocrystalline Silicon with NH4OH and Ion Implantation for Applications in Solar Cells Compatible with CMOS Technology

AbstractThis work presents the development of photovoltaic cells based on p+/n junction in Si substrates, aimed at compatibility with fabrication processes with CMOS technology. The compatible processes, which are developed in this study, are the techniques:i) Si surface texturing, with the textured surface reflection of 15% obtained by the formation of micro-pyramids (heights between 3 and 7μm) using NH4OH (ammonium hydroxide) alkaline solution, which is free of undesirable contamination by Na+ and K+ ions, when NaOH and KOH traditional solutions are used, respectively, and ii) of the ECR-CVD (ElectronCyclotron Resonance - Chemical Vapor Deposition) deposition of SiNx (silicon nitride) anti-reflective coating (ARC), which is carried out at room temperature and can be performed after the end of cell fabrication without damage on metallic tracks and without variation of p+/n junction depth. The ARC coating characterization presented that the silicon nitride has a refractive index of 1.92 and a minimum reflectance of 1.03%, which is an excellent result for application in solar (or photovoltaic) cells. For the formation of the pn junction was used ion implantation process with 11B+, E=20KeV, dose of 1x1015cm2 and four rotations of 90° to get uniformity on texturized surfaces

Characterization And Modeling Of Antireflective Coatings Of Si O 2, Si3 N4, And Si Ox Ny Deposited By Electron Cyclotron Resonance Enhanced Plasma Chemical Vapor Deposition

In this work the optical transmission spectra of silicon oxide (Si O2), silicon nitrides (Si3 N4), silicon-rich oxynitrides (Si Ox Ny), and antireflective coatings (ARCs), deposited by the electron cyclotron resonance enhanced plasma chemical vapor deposition onto a silicon substrate at room temperature, are studied. Simulations carried out with the MATHEMATICA program, from 0 to 1000 nm thick coatings, showed maximum transmittance in the three basic colors at 620, 480, and 560 nm for the Si O2, Si3 N4, and Si Ox Ny ARCs, respectively. However, a highly significant transmittance over a broad spectral range from visible (VIS) to near the infrared region, with optical gain in the three basic colors above 20%, is observed only at thicknesses of 80, 70, and 60 nm, respectively, for Si O2, Si3 N4, and Si Ox Ny ARCs. Among the three evaluated films, the highest transmittance in the broad spectral band in the VIS range was observed for 60 nm thick Si3 N4 films. The Fourier transform infrared spectroscopy of these films reveal high structural quality and the presence of Si-O, Si-H, N-H, and Si-N bonds, independent of thickness and deposition parameters. © 2006 American Vacuum Society.242823827White, M., Lampe, D., Blaha, F., Mack, I., (1974) IEEE J. Solid-State Circuits, SC-9, p. 1Furumiya, M., Ohkubo, H., Muramatsu, Y., Kurosawa, S., Okamoto, F., Fujimoto, Y., Nakashiba, Y., (2001) IEEE Trans. Electron Devices, 48, p. 2221Popov, O.A., Waldron, H., (1989) J. Vac. Sci. Technol. A, 7, p. 914Heavens, O.S., (1991) Optical Properties of Thin Solid Films, , Dover, New YorkAroutiounian, V.M., Maroutyan, K.R., Zatikyan, A.L., Touryan, K.J., (2002) Thin Solid Films, 403, p. 517Edwards, D.F., (1985) Handbook of Optical Constants of Solids, , edited by E. D.Palik (Academic, Washington, D.CGreen, M.L., Gusev, E.P., Degraeve, R., Garfunkel, E.L., (2001) J. Appl. Phys., 90, p. 2057Alayo, M.I., Pereyra, I., Scopel, W.L., Fantini, M.C.A., (2002) Thin Solid Films, 402, p. 154Tsu, D.V., Lucovsky, G., Mantini, M.J., Chao, S.S., (1987) J. Vac. Sci. Technol. A, 5, p. 1998Lucovsky, G., Richard, P.D., Tsu, D.V., Lin, S.Y., Markunas, J., (1986) J. Vac. Sci. Technol. A, 4, p. 681Joseph, E.A., Gross, C., Liu, H.Y., Laaksonen, R.T., Celii, F.G., (2001) J. Vac. Sci. Technol. A, 19, p. 2483Wu, X., Ossadnik, Ch., Eggs, Ch., Veprek, S., Phillipp, F., (2002) J. Vac. Sci. Technol. B, 20, p. 1368Diniz, J.A., Do Couto, A.L., Danilov, I., Tatsch, P.J., Swart, J.W., (1999) Proceedings of the XIV International Conference of Microelectronics and Packaging, p. 164Tsu, D.V., Lucovsky, G., Mantini, M.J., (1986) Phys. Rev. B, 33, p. 7069Denisse, C.M.M., Troost, K.Z., Oude Elferink, J.B., Habraken, F.H.P.M., Van Der Weg, W.F., (1986) J. Appl. Phys., 60, p. 253

Thin Titanium Oxide Films Obtained By Rtp And By Sputtering

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)In this paper, two methods to obtain titanium oxide (TiO2) thin films are compared. In the first method metallic titanium (Ti) is deposited by sputtering and then oxidized by rapid thermal process (RTP) in an oxygen atmosphere to form the TiO2 thin films. The second method consists in TiO2 deposition by reactive sputtering. Structural characterization of the prepared samples shows the rutile crystal structure for both films, but TiO2 thin film deposited by sputtering also presented anatase crystal structure. Capacitors were fabricated and the electrical characterization of TiO2 films realized in order 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.FAPESP; São Paulo Research FoundationFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Bunjongpru, W., Sungthong, A., Porntheeraphat, S., Rayanasukha, Y., Pankiew, A., Jeamsaksiri, W., Srisuwan, A., Nukeaw, J., Very low drift and high sensitivity of nanocrystal-TiO2 sensing membrane on pH-ISFET fabricated by CMOS compatible process (2013) Appl. Surf Sci., 267, pp. 206-211. , FebChou, J.-C., Yang, H.-Y., Chen, C.-W., Glucose biosensor of ruthenium-doped TiO2 sensing electrode by co-sputtering system (2010) Microelectron. Reliab., 50 (5), pp. 753-756. , MayBarros, A.D., (2013) Developement of TiOx and ZnO Thin Films for ISFET and SAW Devices, , PhD Thesis, School of Electrical and Compuer Engineering, University of Camp in asSouza, J.F., Moreira, M.A., Doi, I., Diniz, A.I., Tatsch, P.J., Gonçalves, J.L., Preparation and characterization of high-k aluminium nitride (A1N) thin film for sensor and integrated circuits applications (2012) Phys. Status Solidi, 9 (6), pp. 1454-1457. , JunOkuya, M., Nakade, K., Kaneko, S., Porous TiO2 thin films synthesized by a spray pyrolysis deposition (SPD) technique and their application to dye-sensitized solar cells (2002) Solar Energy Materials & Solar Cells, 70, pp. 425-435Oja, I., Chemical solution deposition of thin TiO2 -anatase films for dielectric applications (2004) Materials Ins Electronics, 5, pp. 341-344Yu, J., Zhao, X., Zhao, Q., Photocatalytic activity of nanometer TiO2 thin films prepared by the sol - gel method (2001) Materials Chemistry and Physsics, 69, pp. 25-29Barros, A.D., Albertin, K.F., Miyoshi, J., Doi, I., Diniz, J.A., Thin titanium oxide films deposited by e-beam evaporation with additional rapid thermal oxidation and annealing for ISFET applications (2010) Microelectron. Eng., 87 (3), pp. 443-446. , MarLai, C.-S., Lu, T.-F., Yang, C.-M., Lin, Y.-C., Pijanowska, D.G., Jaroszewicz, B., Body effect minimization using single layer structure for pH-ISFET applications (2010) Sensors and Actuators B Chem., 143 (2), pp. 494-499. , JanHenson, W.K., Ahmed, K.Z., Vogel, E.M., Hauser, J.R., Wortman, J.J., Venables, R.D., Xu, M., Venables, D., Estimating oxide thickness of tunnel oxides down to 1.4 nm using conventional capacitance-voltage measurements on MOS capacitors (1999) IEEE Electron Device Lett., 20 (4), pp. 179-181. , AprHauser, J.R., Ahmed, K., Characterization of ultra-thin oxides using electrical C-V and I-V measurements (1998) 1998 Int. Conf. Charact. Metrol. ULSI Technol., 235 (1998), pp. 235-239Chou, J.-C., Liao, L.P., Study on pH at the point of zero charge of TiO2 pH ion-sensitive field effect transistor made by the sputtering method (2005) Thin Solid Films, 476 (1), pp. 157-161. , AprKadoshima, M., Hiratani, M., Shimamoto, Y., Torii, K., Miki, H., Rutile-type TiO2 thin film for high-k gate insulator (2003) Thin Solid Films, 424, pp. 224-228Frank, M.M., Kim, S., Brown, S.L., Bruley, J., Copel, M., Hopstaken, M., Chudzik, M., Narayanan, V., Scaling the MOSFET gate dielectric: From high-k to higher-k? (2009) Microelectron. Eng., 86 (7-9), pp. 1603-1608. , JulKim, S., Brown, S.L., Rossnagel, S.M., Bruley, J., Copel, M., Hopstaken, M.J.P., Narayanan, V., Frank, M.M., Oxygen migration in TiO2 based higher-k gate stacks (2010) J Appl. Phys., 107 (5), p. 05410

Causes of morphological discontinuities in soils of Depressão Central, Rio Grande do Sul State, Brazil

Morphological, particularly textural, discontinuities between horizons increase soil erodibility in Depressão Central, Rio Grande do Sul State (Brazil). Characterization of such discontinuities would help to understand landscape evolution and to model near-surface hydrology. The objective of this research was to explore the relationship between morphological discontinuity and deposition of transported materials during pedogenesis. Transported material was meant to be mineral particles found in the soil profile, transported probably by water or gravity, that were not present neither in the parent material nor derived from it. Five soils of this region (two Alfisols, two Ultisols and one Mollisol) were sampled and morphological, sand grain size statistics, chemical and mineralogical analyses were used to search for evidences of deposition of transported materials. Two soils had abrupt textural change but no evidence of deposition of transported materials, two soils had less contrasting morphology and some characteristics that are possibly related to deposition, and one soil had no morphological discontinuity, but had deposition of material enriched in magnetite-maghemite in the sand fraction of the A horizon. Therefore, there were no relationship between morphological discontinuity and deposition of transported materials for these profiles in the Depressão Central.Contrastes morfológicos entre horizontes, e particularmente os contrastes texturais, aumentam a erodibilidade do solo na Depressão Central do Rio Grande do Sul (Brasil). A caracterização destes contrastes contribui para a compreensão da evolução da paisagem e para a modelagem da hidrologia de superfície. Cinco solos desta região foram amostrados e a morfologia, distribuição do tamanho de grãos da fração areia, análises químicas e mineralógicas foram usadas para tentativamente relacionar o contraste textural e morfológico com materiais transportados durante a pedogênese. Por materiais transportados entendem-se as partículas minerais presentes no perfil do solo, transportadas provavelmente por água ou gravidade, e que não estavam presentes nem no material de origem e nem foram derivadas deste. Dois solos apresentaram mudança textural abrupta sem evidências de deposição, dois solos apresentaram menor contraste morfológico e evidências que sustentam a possibilidade de deposição e um solo não apresentou contraste morfológico, porém as características indicam deposição de material rico em magnetita-maghemita na fração areia do horizonte A. Portanto, não foi encontrada relação entre descontinuidades morfológicas e deposição de materiais transportados, na Depressão Central

Measurement of the Bs0→J/ψKS0B_s^0\to J/\psi K_S^0 branching fraction

The $B_s^0\to J/\psi K_S^0$ branching fraction is measured in a data sample corresponding to 0.41$fb^{-1}$ of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to the penguin contributions affecting the sin2$\beta$ measurement from $B^0\to J/\psi K_S^0$ The time-integrated branching fraction is measured to be $BF(B_s^0\to J/\psi K_S^0)=(1.83\pm0.28)\times10^{-5}$. This is the most precise measurement to date

Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6, 9 and 10 and corresponding explanation in the tex

Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented.Comment: 48 pages, 19 figures. Results unchanged, improved clarity of Table 6, 9 and 10 and corresponding explanation in the tex