Characterization of the interface between highly conductive Ga:ZnO films and the silicon substrate

Work in collaboration with the Nanotech Unit, Department of Applied Physics I, University of Malaga, Spain.

M. Gabás, E. Ochoa-Martínez, E. Navarrete-Astorga, A. R. Landa-Cánovas, P. Herrero, F. Agulló-Rueda, S. Palanco, J. J. Martínez-Serrano, and J. R. Ramos-Barrado, “Characterization of the interface between highly conductive Ga:ZnO films and the silicon substrate,” Appl. Surf. Sci. 419, 595–602 (2017)

Gallium-doped zinc oxide films are an interesting alternative for transparent conductive materials. To improve their performance, the interface between the grown layer and the substrate must be fully understood. Accordingly, ZnO and Ga:ZnO films have been deposited onto p-type doped Si (111) substrates by magnetron sputtering for 1, 2, 3 and 20 min and their interfaces characterized by transmission electron microscopy, photoelectron spectroscopy, spectroscopic ellipsometry and impedance spectroscopy. The combination of transmission electron microscopy techniques suggested a more complex interface chemistry in the Ga:ZnO/Si case, a point confirmed by x-ray photoelectron spectroscopy measurements on very thin films. While the ZnO/Si interface consists mostly of silicon oxides, zinc silicates and some Zn0, the Ga:ZnO/Si interface, besides these constituents, has a noticeable amount of Ga:ZnO and small quantities of Ga0. The band alignment deduced from the photoelectron spectroscopy measurements, together with the layers and Si band gap values, evidences a higher work function for the doped film and a smaller conduction band barrier for the Ga:ZnO/Si interface. Concerning the optical and electrical characteristics, spectroscopic ellipsometry revealed no significant differences between the two interfaces, while impedance spectroscopy measurements demonstrated that the Ga:ZnO/Si interface is less resistive than the ZnO/Si one.

Publicado en HRTEM, microscopy, nanocharacterization, nanoscience, nanotechnology, Publications, transparent conductive oxides, zinc oxide | Etiquetado , , , , , , | Deja un comentario

Micro-Raman spectroscopy of near-surface damage in diamond irradiated with 9-MeV boron ions

F. Agulló-Rueda, M. D. Ynsa, N. Gordillo, A. Maira, D. Moreno-Cerrada, and M. A. Ramos, “Micro-Raman spectroscopy of near-surface damage in diamond irradiated with 9-MeV boron ions,” Diamond Relat. Mater. 72, 94–98 (2017)

GraphicalAbstract2016DRM04smallWe have studied the near-surface damage in a diamond crystal caused by irradiation with swift boron ions and its healing after high-temperature annealing. A diamond crystal was irradiated with 9-MeV 11B3 + ions with fluence values between 1 × 1015 and 4.42 × 1016 ions/cm2 to generate various levels of lattice damage. The ions loose energy to the lattice and, according to simulations, stop at a depth of about 5 μm, where they form a thin buried implantation layer. For the near-surface layers damage is produced by the ions at high kinetic energy before they slow down. Only intrinsic defects can be produced, with no boron atoms. The lattice damage of the near-surface layers and its recovery after annealing for 1 hour at 1000°C were studied by Raman and photoluminescence spectroscopies. Back-scattered light from a 514.5-nm laser beam was collected from the sample surface, probing a depth of a few micrometers. We observe some disordering of the lattice plus the formation of neutral vacancies, interstitial and other lattice defects. After annealing the Raman spectrum shows a significant recovery of the lattice order and the disappearance of isolated neutral vacancies. Residual damage is confirmed by the luminescence spectrum, that shows the appearance of new spectral features.

Publicado en diamond, ion irradiation, microscopy, nanocharacterization, photoluminescence, Raman spectroscopy | Deja un comentario

Study of the formation mechanism of hierarchical silicon structures produced by sequential ion beam irradiation and anodic etching

In a collaboration with the Autonomous University of Madrid (Department of Applied Physics and the Center for Micro Analysis of Materials) and the Institut für Solarenergieforschung Hameln (ISFH) of Germany we have studied the formation of micropatterns combining nanostructured (porous) Si (NPSi) and bulk Si by a sequential process of selective high energy ion irradiation and anodic etching.

E. Punzón Quijorna, S. Kajari-Shrönder, F. Agulló-Rueda, M. Manso Silván, R. J. Martín Palma, P. Herrero Fernández, V. Torres-Costa, and A. Climent, “Study of the formation mechanism of hierarchical silicon structures produced by sequential ion beam irradiation and anodic etching,” Vacuum 138, 238–243 (2017).

Publicado en HRTEM, ion irradiation, microscopy, nanocharacterization, nanoscience, nanotechnology, Raman spectroscopy, silicon | Deja un comentario

Direct laser writing of nanorough cell microbarriers

In collaboration with the Advanced Photonic and Biofunctional Materials group the Autonomous University of Madrid, lead by Dr. Miguel Manso, we have studied by Raman microspectroscopy laser written silicon-based structures for biological cell microbarriers.

Y. Xiang, R. Martínez Martínez, V. Torres-Costa, F. Agulló-Rueda, J. P. Garcia-Ruiz, and M. Manso Silván, “Direct laser writing of nanorough cell microbarriers on anatase/Si and graphite/Si,” Mater. Sci. Eng. C 66, 8–15 (2016)

Publicado en microscopy, nanocharacterization, nanoscience, nanotechnology, Publications, Raman spectroscopy, silicon | Etiquetado , , , | Deja un comentario

Variability of silkworm silk and degumming

In collaboration with the Department of Materials Science of the Polytechnical University of Madrid we have studied by Raman spectroscopy as spun silkworm (Bombyx mori) silk fibers subjected to different degumming treatments.

G. B. Perea, C. Solanas, N. Marí-Buyé, R. Madurga, F. Agulló-Rueda, A. Muinelo, C. Riekel, M. Burghammer, I. Jorge, J. Vázquez, G. R. Plaza, A. Torres, F. del Pozo, G. V. Guinea, M. Elices, J. L. Cenis, and J. Pérez-Rigueiro, “The apparent variability of silkworm (Bombyx mori) silk and its relationship with degumming,” Eur. Polym. J., 78, 129–140 (2016).

Publicado en microscopy, Publications, Raman spectroscopy, silk | Etiquetado , , , | Deja un comentario

Jon Canca Ruiz has joined our group

Jon Canca Ruiz graduated in Chemistry from the University of the Basque Country. He has a Master on New Materials from the same university. He has worked on the synthesis and x-ray diffraction characterization of hybrid polyoxomethalates/metalorganic single crystals.

Publicado en People | Deja un comentario

Laser heating induced phase changes of VO2

Vilanova2015GraphicalAbstract

P. Vilanova-Martínez, J. Hernández-Velasco, A. R. Landa-Cánovas, and F. Agulló-Rueda, “Laser heating induced phase changes of VO2 crystals in air monitored by Raman spectroscopy,” J. Alloys Comp. 661, 122–125 (2016)

Publicado en HRTEM, Publications, Raman spectroscopy, Sin categoría | Etiquetado , , , , , , , | Deja un comentario

HRTEM microscopy of transformations in bulk amorphous silica produced by ultrafast laser direct writing

A transmission electron microscopy study of nanogratings formed in bulk amorphous silica by direct writing with an ultrafast pulsed laser with a radiation wavelength of 1030 nm and pulse duration of 560 fs is presented. The results achieved show that the nanogratings are composed of planar nanostructures with an average periodicity of 250 nm and typical thickness of about 30 nm, consisting of alternating layers of heavily damaged material and layers of material where a dense precipitation of nanocrystals occurred. The crystallization of silica to form these nanocrystals can be explained by the large pressures and temperatures reached in these regions as a result of nanoplasma formation and recombination.

Collaboration with Instituto Superior de Engenharia de Lisboa, ICEMS—Instituto de Ciência e Engenharia de Materiais e Superfícies, and Instituto Superior Técnico, Lisbon, Portugal.

Vitor Oliveira, Sahendra P. Sharma, Pilar Herrero, and Rui Vilar, “Transformations induced in bulk amorphous silica by ultrafast laser direct writing,” Opt. Lett. 38, 4950 (2013).

Publicado en HRTEM, microscopy, nanocharacterization, nanoscience, nanotechnology, Sin categoría | Deja un comentario

Chemical analysis of pigments in Velazquez paintings

The journal Vibrational Spectroscopy has published a work of us in collaboration with researchers Carolina Gutiérrez and Aurelio Climent, from the Autonomous University of Madrid (UAM), and Carmen Garrido, from the Prado Museum. In this work we have studied the chemical composition and the crystal structure of pigments in Diego Velazquez paintings from different periods in the artist life. Using Raman microspectroscopy we have found that the number of pigments was very limited and did not change significantly during the artist lifetime. P. C. Gutiérrez, F. Agulló-Rueda, A. Climent-Font, and C. Garrido, “Identification of pigments in Diego Velázquez paintings by Raman microscopy,” Vibrat. Spec. 69, 13–20 (2013)

La revista Vibrational Spectroscopy acaba de publicar un trabajo nuestro realizado en colaboración con los investigadores Carolina Gutiérrez y Aurelio Climent, de la Universidad Autónoma de Madrid (UAM), y Carmen Garrido, del Museo del Prado. En este trabajo hemos estudiado la composición química y la estructura cristalina de pigmentos en las pinturas de Diego Velazquez procedentes de distintos periodos en la vida del artista. Mediante microespectroscopía Raman hemos encontrado una paleta reducida de pigmentos que no cambió de forma significativa a lo largo de la vida del artista. P. C. Gutiérrez, F. Agulló-Rueda, A. Climent-Font, and C. Garrido, “Identification of pigments in Diego Velázquez paintings by Raman microscopy,” Vibrat. Spec. 69, 13–20 (2013)

Publicado en art, microscopy, Publications, Raman spectroscopy | Deja un comentario

Microscopy course starts on May 16th, 2013

The course Microscopy in Materiales Science: TEM and Raman 2013 is scheduled from May 16th to May 24th, 2013, at the Materials Science Institute of Madrid (ICMM-CSIC). The classes will be held in the afternoon. More details in the course webpage.El curso Microscopía en Ciencia de Materiales: TEM y Raman 2013 está programado del 16 al 24 de mayo de 2013. Las clases se impartirán por las tardes en el Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). Más información en la página web del curso.

Publicado en course, education, microscopy, Sin categoría, teaching | Deja un comentario