Photoluminescent properties of electrochemically synthetized ZnO nanotubes

ZnO nanotubes were prepared by a sequential combination of electrochemical deposition, chemical attack and regeneration. ZnO nanocolumns were initially electrodeposited on conductive substrates and then converted into nanotubes by a process involving chemical etching and subsequent regrowth. The morphology of these ZnO nanocolumns and derived nanotubes was monitored by Scanning Electron Microscopy and their optical properties was studied by photoluminescence spectroscopy. Photoluminescence were measured as a function of temperature, from 6 to 300 K, for both nanocolumns and nanotubes. In order to study the behaviour of induced intrinsic defect all ZnO films were annealed in air at 400 °C and their photoluminescent properties were also registered before and after annealing. The behaviour of photoluminescence is explained taking into account the contribution of different point defects. A band energy diagram related to intrinsic defects was proposed to describe the behaviour of photoluminescence spectraThis work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R) and Generalitat Valenciana (Prometeus 2014/044).Gracia Jimenez, JM.; Cembrero Cil, J.; Mollar García, MA.; Marí Soucase, B. (2016). Photoluminescent properties of electrochemically synthetized ZnO nanotubes. Materials Characterization. 119:152-158. https://doi.org/10.1016/j.matchar.2016.07.022S15215811

ZnO Nanoestructured Layers Processing with Morphology Control by Pulsed Electrodeposition

The fabrication of nanostructured ZnO thin films is a critic process for a lot of applications of this semiconductor material. The final properties of this film depend fundamentally of the morphology of the sintered layer. In this paper a process is presented for the fabrication of ZnO nanostructured layers with morphology control by pulsed electrodeposition over ITO. Process optimization is achieved by pulsed electrodeposition and results are assessed after a careful characterization of both morphology and electrical properties. SEM is used for nucleation analysis on pulsed deposited samples. Optical properties like transmission spectra and Indirect Optical Band Gap are used to evaluate the quality of the obtained ZnO structures.Reyes Tolosa, MD.; Orozco Messana, J.; Damonte ., LC.; Hernández Fenollosa, MDLÁ. (2011). ZnO Nanoestructured Layers Processing with Morphology Control by Pulsed Electrodeposition. Journal of The Electrochemical Society. 158(7):452-455. doi:10.1149/1.35930044524551587Fath, P., Nussbaumer, H., & Burkhardt, R. (2002). Industrial manufacturing of semitransparent crystalline silicon POWER solar cells. Solar Energy Materials and Solar Cells, 74(1-4), 127-131. doi:10.1016/s0927-0248(02)00056-9Bruton, T. . (2002). General trends about photovoltaics based on crystalline silicon. Solar Energy Materials and Solar Cells, 72(1-4), 3-10. doi:10.1016/s0927-0248(01)00145-3Geiger, P., Hahn, G., Fath, P., & Bucher, E. (2002). Comparing improved state-of-the-art to former EFG Si-ribbons with respect to solar cell processing and hydrogen passivation. Solar Energy Materials and Solar Cells, 72(1-4), 155-163. doi:10.1016/s0927-0248(01)00160-xDonderis, V., Orozco, J., Cembrero, J., Curiel-Esparza, J., Damonte, L. C., & Hernández-Fenollosa, M. A. (2010). Doped Nanostructured Zinc Oxide Films Grown by Electrodeposition. Journal of Nanoscience and Nanotechnology, 10(2), 1387-1392. doi:10.1166/jnn.2010.1869Xu, L., Guo, Y., Liao, Q., Zhang, J., & Xu, D. (2005). Morphological Control of ZnO Nanostructures by Electrodeposition. The Journal of Physical Chemistry B, 109(28), 13519-13522. doi:10.1021/jp051007bZ. Zhanxia, Z. Yan, Y. Huacong, and M. Zhongquan , INEC Nanoelectronics Conference 2008. IEEE InternationalDu, Y., Zhang, M.-S., Wu, J., Kang, L., Yang, S., Wu, P., & Yin, Z. (2003). Optical properties of SrTiO 3 thin films by pulsed laser deposition. Applied Physics A: Materials Science & Processing, 76(7), 1105-1108. doi:10.1007/s00339-002-1998-zNakajima, A., Sugita, Y., Kawamura, K., Tomita, H., & Yokoyama, N. (1996). Si Quantum Dot Formation with Low-Pressure Chemical Vapor Deposition. Japanese Journal of Applied Physics, 35(Part 2, No. 2B), L189-L191. doi:10.1143/jjap.35.l189Pauporté, T., & Lincot, D. (2000). Electrodeposition of semiconductors for optoelectronic devices: results on zinc oxide. Electrochimica Acta, 45(20), 3345-3353. doi:10.1016/s0013-4686(00)00405-9Könenkamp, R., Word, R. C., & Godinez, M. (2005). Ultraviolet Electroluminescence from ZnO/Polymer Heterojunction Light-Emitting Diodes. Nano Letters, 5(10), 2005-2008. doi:10.1021/nl051501rMarí, B., Manjón, F. J., Mollar, M., Cembrero, J., & Gómez, R. (2006). Photoluminescence of thermal-annealed nanocolumnar ZnO thin films grown by electrodeposition. Applied Surface Science, 252(8), 2826-2831. doi:10.1016/j.apsusc.2005.04.024Marí, B., Cembrero, J., Manjón, F. J., Mollar, M., & Gómez, R. (2005). Raman measurements on nanocolumnar ZnO crystals. physica status solidi (a), 202(8), 1602-1605. doi:10.1002/pssa.200461196Wang, Q., Wang, G., Jie, J., Han, X., Xu, B., & Hou, J. G. (2005). Annealing effect on optical properties of ZnO films fabricated by cathodic electrodeposition. Thin Solid Films, 492(1-2), 61-65. doi:10.1016/j.tsf.2005.06.046Marı́, B., Mollar, M., Mechkour, A., Hartiti, B., Perales, M., & Cembrero, J. (2004). Optical properties of nanocolumnar ZnO crystals. Microelectronics Journal, 35(1), 79-82. doi:10.1016/s0026-2692(03)00227-1Wang, J., Du, G., Zhang, Y., Zhao, B., Yang, X., & Liu, D. (2004). RETRACTED: Luminescence properties of ZnO films annealed in growth ambient and oxygen. Journal of Crystal Growth, 263(1-4), 269-272. doi:10.1016/j.jcrysgro.2003.11.059Leiter, F., Alves, H., Pfisterer, D., Romanov, N. G., Hofmann, D. M., & Meyer, B. K. (2003). Oxygen vacancies in ZnO. Physica B: Condensed Matter, 340-342, 201-204. doi:10.1016/j.physb.2003.09.031Pauporté, T., Bedioui, F., & Lincot, D. (2005). Nanostructured zinc oxide–chromophore hybrid films with multicolored electrochromic properties. J. Mater. Chem., 15(15), 1552-1559. doi:10.1039/b416419

Electrodeposition of zinc oxide nanostructured films

ZnO nanostructures have great promise in a wide range of applications such as sensors, optoelectronics, piezoelectronics, healthcare. Preparation of oxide films by electrodeposition from aqueous solution presents several advantages over other techniques such as controlling the rate and morphology through several well-defined parameters (electrode potential, current, temperature, pH, etc.), the fact that electrolytic processing is a well-established technology and readily scalable for production, and the non-equilibrium nature of the electrochemical interface often gives rise to morphologies and compositions not attainable through other, usually high-temperature, routes. Despite a large amount of research in this area the detailed mechanism of nucleation and growth is still controversial. Only a good understanding of it will allow the expected industrial applications to be achieved. One of the main difficulties to overcome is that tiny amounts of material are involved and the required in-situ measurements are thus very delicate. The ability of synchrotron radiation to probe material structure during deposition makes it the ideal tool for the study of nucleation and growth of these materials as a function of the processing parameters. Here we will present two synchrotron-based approaches involving both X-ray absorption and scattering. The first method, together with ex-situ characterisation, provides detailed information about how the kinetics of the growth and/or dissolution is influenced by the electrochemical parameters. The effect of time, potential, zinc ions concentration, oxygen precursor, temperature and electrolyte composition have been studied. Following this understanding of the influence of the parameters, films of desired structure can be synthesised and new structures have been made. Beside the electrochemical parameters, the growth of the film is influenced by the interaction with substrate in the early stage of nucleation. The second synchrotron technique allows the direct observation of the development of the crystal orientation of the films during the deposition. It gives promising results to study how the substrate influences the growth and thus the properties of the films

Coherent X-ray di�ffraction imaging of zinc oxide crystals

Zinc Oxide (ZnO) exhibits a plethora of physical properties potentially advantageous in many roles and is why it one of the most studied semiconductor compounds. When doped or in its intrinsic state ZnO demonstrates a multitude of electronic, optical and magnetic properties in a large variety of manufacturable morphologies. Thus it is inherently important to understand why these properties arise and the impact potentially invasive sample preparation methods have for both the function and durability of the material and its devices. Coherent X-ray Diff�raction Imaging (CXDI) is a recently established non-destructive technique which can probe the whole three dimensional structure of small crystalline materials and has the potential for sub angstrom strain resolution. The iterative methods employed to overcome the `phase problem' are described fully. CXDI studies of wurtzite ZnO crystals in the rod morphology with high aspect ratio are presented. ZnO rods synthesised via Chemical Vapour Transport Deposition were studied in post growth state and during in-situ modifi�cation via metal evaporation processing and annealing. Small variations in post growth state were observed, the physical origin of which remains unidentifi�ed. The doping of a ZnO crystal with Iron, Nickel and Cobalt by thermal evaporation and subsequent annealing was studied. The evolution of diff�using ions into the crystal lattice from was not observed, decomposition was found to be the dominant process. Improvements in experimental technique allowed multiple Bragg reflections from a single ZnO crystal to be measured for the fi�rst time. Large aspect ratio ZnO rods were used to probe the coherence properties of the incident beam. The longitudinal coherence function of the illuminating radiation was mapped using the visibility of the interference pattern at each bragg reflection and an accurate estimate of the longitudinal coherence length obtained, \xi(L) = 0.66\pm 0.02 \mu m. The consequences for data analysis are discussed. The combination of multiple Bragg reflections to realise three dimensional displacement �fields was also approached

ZnO Nanoestructured Layers Processing with Morphology Control by Pulsed Electrodeposition

The fabrication of nanostructured ZnO thin films is a critic process for a lot of applications of this semiconductor material. The final properties of this film depend fundamentally of the morphology of the sintered layer. In this paper a process is presented for the fabrication of ZnO nanostructured layers with morphology control by pulsed electrodeposition over ITO. Process optimization is achieved by pulsed electrodeposition and results are assessed after a careful characterization of both morphology and electrical properties. SEM is used for nucleation analysis on pulsed deposited samples. Optical properties like transmission spectra and Indirect Optical Band Gap are used to evaluate the quality of the obtained ZnO structures.Reyes Tolosa, MD.; Orozco Messana, J.; Damonte ., LC.; Hernández Fenollosa, MDLÁ. (2011). ZnO Nanoestructured Layers Processing with Morphology Control by Pulsed Electrodeposition. Journal of The Electrochemical Society. 158(7):452-455. doi:10.1149/1.35930044524551587Fath, P., Nussbaumer, H., & Burkhardt, R. (2002). Industrial manufacturing of semitransparent crystalline silicon POWER solar cells. Solar Energy Materials and Solar Cells, 74(1-4), 127-131. doi:10.1016/s0927-0248(02)00056-9Bruton, T. . (2002). General trends about photovoltaics based on crystalline silicon. Solar Energy Materials and Solar Cells, 72(1-4), 3-10. doi:10.1016/s0927-0248(01)00145-3Geiger, P., Hahn, G., Fath, P., & Bucher, E. (2002). Comparing improved state-of-the-art to former EFG Si-ribbons with respect to solar cell processing and hydrogen passivation. Solar Energy Materials and Solar Cells, 72(1-4), 155-163. doi:10.1016/s0927-0248(01)00160-xDonderis, V., Orozco, J., Cembrero, J., Curiel-Esparza, J., Damonte, L. C., & Hernández-Fenollosa, M. A. (2010). Doped Nanostructured Zinc Oxide Films Grown by Electrodeposition. Journal of Nanoscience and Nanotechnology, 10(2), 1387-1392. doi:10.1166/jnn.2010.1869Xu, L., Guo, Y., Liao, Q., Zhang, J., & Xu, D. (2005). Morphological Control of ZnO Nanostructures by Electrodeposition. The Journal of Physical Chemistry B, 109(28), 13519-13522. doi:10.1021/jp051007bZ. Zhanxia, Z. Yan, Y. Huacong, and M. Zhongquan , INEC Nanoelectronics Conference 2008. IEEE InternationalDu, Y., Zhang, M.-S., Wu, J., Kang, L., Yang, S., Wu, P., & Yin, Z. (2003). Optical properties of SrTiO 3 thin films by pulsed laser deposition. Applied Physics A: Materials Science & Processing, 76(7), 1105-1108. doi:10.1007/s00339-002-1998-zNakajima, A., Sugita, Y., Kawamura, K., Tomita, H., & Yokoyama, N. (1996). Si Quantum Dot Formation with Low-Pressure Chemical Vapor Deposition. Japanese Journal of Applied Physics, 35(Part 2, No. 2B), L189-L191. doi:10.1143/jjap.35.l189Pauporté, T., & Lincot, D. (2000). Electrodeposition of semiconductors for optoelectronic devices: results on zinc oxide. Electrochimica Acta, 45(20), 3345-3353. doi:10.1016/s0013-4686(00)00405-9Könenkamp, R., Word, R. C., & Godinez, M. (2005). Ultraviolet Electroluminescence from ZnO/Polymer Heterojunction Light-Emitting Diodes. Nano Letters, 5(10), 2005-2008. doi:10.1021/nl051501rMarí, B., Manjón, F. J., Mollar, M., Cembrero, J., & Gómez, R. (2006). Photoluminescence of thermal-annealed nanocolumnar ZnO thin films grown by electrodeposition. Applied Surface Science, 252(8), 2826-2831. doi:10.1016/j.apsusc.2005.04.024Marí, B., Cembrero, J., Manjón, F. J., Mollar, M., & Gómez, R. (2005). Raman measurements on nanocolumnar ZnO crystals. physica status solidi (a), 202(8), 1602-1605. doi:10.1002/pssa.200461196Wang, Q., Wang, G., Jie, J., Han, X., Xu, B., & Hou, J. G. (2005). Annealing effect on optical properties of ZnO films fabricated by cathodic electrodeposition. Thin Solid Films, 492(1-2), 61-65. doi:10.1016/j.tsf.2005.06.046Marı́, B., Mollar, M., Mechkour, A., Hartiti, B., Perales, M., & Cembrero, J. (2004). Optical properties of nanocolumnar ZnO crystals. Microelectronics Journal, 35(1), 79-82. doi:10.1016/s0026-2692(03)00227-1Wang, J., Du, G., Zhang, Y., Zhao, B., Yang, X., & Liu, D. (2004). RETRACTED: Luminescence properties of ZnO films annealed in growth ambient and oxygen. Journal of Crystal Growth, 263(1-4), 269-272. doi:10.1016/j.jcrysgro.2003.11.059Leiter, F., Alves, H., Pfisterer, D., Romanov, N. G., Hofmann, D. M., & Meyer, B. K. (2003). Oxygen vacancies in ZnO. Physica B: Condensed Matter, 340-342, 201-204. doi:10.1016/j.physb.2003.09.031Pauporté, T., Bedioui, F., & Lincot, D. (2005). Nanostructured zinc oxide–chromophore hybrid films with multicolored electrochromic properties. J. Mater. Chem., 15(15), 1552-1559. doi:10.1039/b416419