Person: González Díaz, Germán
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First Name
Germán
Last Name
González Díaz
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Estructura de la Materia, Física Térmica y Electrónica
Area
Electrónica
Identifiers
39 results
Search Results
Now showing 1 - 10 of 39
Item Compositional analysis of SiOxNy : H films by heavy-ion ERDA: the problem of radiation damage(Surface and interface analysis, 2002) Mártil de la Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro del; San Andrés Serrano, EnriqueFilms of SiOxNy:H were deposited at room temperature on Si substrates by the electron cyclotron resonance (ECR) plasma method. By varying the flow rates of the precursor gases SiH4, O-2. and N-2, the whole composition range between pure silicon oxide and nitride could be covered. Heavy-ion elastic recoil detection analysis (HI-ERDA) with a 150 MeV Kr-86 ion beam and time-of-flight (ToF) mass separation was applied to determine the absolute atomic concentrations of all film components, including hydrogen. Additionally, the bonding configuration of the films was studied by infrared (IR) spectroscopy. Extended ion beam exposure was found to decrease the intensity of the N-H phonon band as well as the nitrogen and hydrogen concentrations. By storing the ion scattering data event by event and by recalculating a zero-dose composition, this effect was taken into account. The corrected Hl-ERDA results revealed clear relations to the deposition parameters (e.g. the O-2/SiH4 flow ratio). The hydrogen incorporated in the films turned out to be bonded predominantly to nitrogen. The damage effects were strongest in the medium composition range. They were found to scale with the relative concentration of SiO2N2-type basic tetrahedrons, suggesting that this bonding configuration is most sensitive against irradiation during the HI-ERDA measurement. Copyright (C) 2002 John Wiley Sons, Ltd.Item A comparative study of anodic tantalum pentoxide and high-pressure sputtered titanium oxide(Journal of Materials Science: Materials in Electronics, 2003) Mártil de la Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro del; San Andrés Serrano, EnriqueIn this work we present a new method to fabricate improved TiO2 films by using a high-pressure sputtering system. In order to minimize the damage induced in the substrate surface by the ion bombardment, a high chamber pressure of 100 Pa is used, which is very much higher than typical values in conventional systems. We present results obtained by Xray diffraction and FTIR spectroscopy. Moreover, we will compare the properties of the resulting TiO2-insulator-metal capacitors with those of anodic Ta2O5. Very thin films of TiO2 have been obtained with a very promising quality for future electron device fabrication.- Project number: 283
Item Integración de la formación teórica y experimental en el área de la Electrónica mediante el desarrollo de una plataforma de demostración del comportamiento real de los circuitos desarrollados en la docencia teórica(2020) San Andrés Serrano, Enrique; González Díaz, Germán; Del Prado Millán, Álvaro; Olea Ariza, Javier; Caudevilla Gutiérrez, Daniel; Herrera Fernández, Fernando; Paz López, Antonio Item Composition and optical properties of silicon oxynitride films deposited by electron cyclotron resonance(Vacuum, 2002) Mártil de la Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro del; San Andrés Serrano, EnriqueSilicon oxynitride films covering the whole composition range from silicon nitride to silicon oxide have been deposited by electron cyclotron resonance chemical vapor deposition from SiH4, O-2 and N-2 gas mixtures. The composition of the films has been determined by heavy-ion elastic recoil detection analysis (HI-ERDA), providing absolute concentrations of all elements, including H, and by Auger electron spectroscopy. Additionally, Fourier transform infrared (FTIR) spectroscopy and ellipsometry measurements have been performed on the same samples for optical characterization. The concentration of the different species (Si, O, N and H) and the density of the films have been calculated and compared to the theoretical values for stoichiometric films. The presence of N-H bonds and non-bonded H results in a significant decrease of the Si concentration with respect to the theoretical value, especially for samples close to silicon nitride composition. The decrease of the Si concentration results in a decrease of both the N and 0 concentrations. The overall result is a decrease of the density and therefore a decrease of the refractive index with respect to stoichiometric films. The total H content determined by ERDA has been compared with the area of the FTIR N-H stretching band, which is frequently used to obtain the H content. It has been found that the calibration factor for this band depends on composition, increasing with increasing the O content.Item Bonding structure and hydrogen content in silicon nitride thin films deposited by the electron cyclotron resonance plasma method(Thin Solid Films, 2004) Mártil de la Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro del; San Andrés Serrano, EnriqueThe bonding structure and hydrogen content of amorphous hydrogenated silicon nitride (a-SiNx:H) thin films have been investigated by infrared spectroscopy and ion beam techniques. Electron cyclotron resonance plasma enhanced chemical vapor deposition was used to produce these films under different values of gas flow ratio, deposition temperature, and microwave power. The amount of bonded hydrogen was calculated from the N-H and Si-H infrared absorption bands. An increase of the SiH4 partial pressure during deposition was found to have the same effect on the H content as an increase of the substrate temperature: both cause a decrease of the N-H bond density and an increase in the number of Si-H bonds. This is explained by a competitive process in the formation of N-H and Si-H bonds during the growth of the film, whereby Si-H bonds are favored at the expense of N-H bonds when either the SiH4 flow or the substrate temperature are increased. Such tendency to chemical order is compared with previous results in which the same behavior was induced by thermal annealing or ion beam bombardment.Item On the Optoelectronic Mechanisms Ruling Ti-hyperdoped Si Photodiodes(Advanced electronic materials, 2022) García Hemme, Eric; Caudevilla Gutiérrez, Daniel; Algaidy, Sari; Pérez Zenteno, Francisco José; García Hernansanz, Rodrigo; Olea Ariza, Javier; Pastor Pastor, David; Prado Millán, Álvaro del; San Andrés Serrano, Enrique; Mártil de la Plaza, Ignacio; González Díaz, GermánThis work deepens the understanding of the optoelectronic mechanisms ruling hyperdoped-based photodevices and shows the potential of Ti hyperdoped-Si as a fully complementary metal-oxide semiconductor compatible material for room-temperature infrared photodetection technologies. By the combination of ion implantation and laser-based methods, approximate to 20 nm thin hyperdoped single-crystal Si layers with a Ti concentration as high as 10(20) cm(-3) are obtained. The Ti hyperdoped Si/p-Si photodiode shows a room temperature rectification factor at +/- 1 V of 509. Analysis of the temperature-dependent current-voltage characteristics shows that the transport is dominated by two mechanisms: a tunnel mechanism at low bias and a recombination process in the space charge region at high bias. A room-temperature sub-bandgap external quantum efficiency (EQE) extending to 2.5 mu m wavelength is obtained. Temperature-dependent spectral photoresponse behavior reveals an increase of the EQE as the temperature decreases, showing a low-energy photoresponse edge at 0.45 eV and a high-energy photoresponse edge at 0.67 eV. Temperature behavior of the open-circuit voltage correlates with the high-energy photoresponse edge. A model is proposed to relate the optoelectronic mechanisms to sub-bandgap optical transitions involving an impurity band. This model is supported by numerical semiconductor device simulations using the SCAPS software.- Project number: 69
Item Mejora de las Metodologías Docentes para el área de la Electrónica(2018) San Andrés Serrano, Enrique; González Díaz, Germán; Mártil de la Plaza, Ignacio; del Prado Millán, Álvaro; García Hemme, Eric; Pastor Pastor, David; Olea Ariza, Javier; Lucía Mulas, María Luisa; Franco Peláez, Francisco Javier; Sánchez Balmaseda, Margarita Item Optical spectroscopic study of the SiN/HfO2 interfacial formation during rf sputtering of HfO2(Applied physics Letters, 2007) Mártil de la Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro del; San Andrés Serrano, EnriqueHigh-k stacks formed by chemical-vapor-deposited SiN and high-pressure sputtered HfO2 in either O-2 or Ar atmosphere have been studied. The introduction of a SiN layer is proposed to prevent the uncontrollable SiO2 growth while sputtering. The formation of Si-O bonds after the sputtering of the HfO2 film in O-2 atmosphere was observed by infrared spectroscopy. Optical diagnosis of the plasma demonstrated a high density of O radicals in the system when working with O-2. The small radius and high reactivity of these O radicals are the source of the SiN oxidation. However, the structure of the SiN film is preserved during Ar sputtering.Item Microstructural modifications induced by rapid thermal annealing in plasma deposited SiOxNyHz films(Journal of Applied Physics, 2003) Mártil de la Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro del; San Andrés Serrano, EnriqueThe effect of rapid thermal annealing (RTA) processes on the structural properties of SiOxNyHz films was investigated. The samples were deposited by the electron cyclotron resonance plasma method, using SiH4, O-2 and N-2 as precursor gases. For SiOxNyHz films with composition close to that of SiO2, which have a very low H content, RTA induces thermal relaxation of the lattice and improvement of the structural order. For films of intermediate composition and of compositions close to SiNyHz, the main effect of RTA is the release of H at high temperatures (T>700degreesC). This H release is more significant in films containing both Si-H and N-H bonds, due to cooperative reactions between both kinds of bonds. In these films the degradation of structural order associated to H release prevails over thermal relaxation, while in those films with only N-H bonds, thermal relaxation predominates. For annealing temperatures in the 500-700degreesC range, the passivation of dangling bonds by the nonbonded H in the films and the transition from the paramagnetic state to the diamagnetic state of the K center result in a decrease of the density of paramagnetic defects. The H release observed at high annealing temperatures is accompanied by an increase of density of paramagnetic defects.Item Interface quality of high-pressure reactive sputtered and atomic layer deposited titanium oxide thin films on silicon(2005 Spanish Conference on Electron Devices, Proceedings, 2005) Mártil de la Plaza, Ignacio; González Díaz, Germán; San Andrés Serrano, EnriqueA comparison between interface quality of several temperatures thermal annealed HPRS TiO2 films and 750 degrees C annealed ALD TiO2 films has been established. Our attention has been focused on the interfacial state and disordered induced gap state densities. From our results, HPRS films submitted to in situ 900 degrees C thermal annealing in oxygen atmosphere exhibit the best characteristics, with D-it, density being the lowest value measured in this work (5 - 6 x 10(11) cm(-2) eV(-1)), and undetectable conductance transients within our experimental limits.