Papers by Gemma García Mandayo
2018 Spanish Conference on Electron Devices (CDE), 2018
Direct laser interference patterning (DLIP) is a fast nanostructuring technique able to generate ... more Direct laser interference patterning (DLIP) is a fast nanostructuring technique able to generate periodic patterns in the submicrometric range, what modifies the morphology and structural properties of semiconductors. DLIP has been used on gas sensors based on ZnO thin film, generating 1D patterns. The nanostructuring has modified the crystal structure and the surface topography. DLIP acts similarly to a thermal treatment from the crystallographic point of view and has been used to detect low concentration of formaldehyde (HCHO). Comparable magnitude of responses (around the 25 % for 20 ppm of formaldehyde) are shown for sensors thermally treated sensors and sensors processed by DLIP.
Sensors and Actuators B: Chemical, 2022
The spring Meeting of the European Materials Research Society (E-MRS) was held from May 27 to 31,... more The spring Meeting of the European Materials Research Society (E-MRS) was held from May 27 to 31, 2019, in Nice, France. Poster tittle: A new laser enhanced aerosol assisted chemical vapor deposition for thin film growth in electro-optical devices.
<strong>Spanish Optoelectronics Meeting (OPTOEL) </strong>hosted in<strong> <... more <strong>Spanish Optoelectronics Meeting (OPTOEL) </strong>hosted in<strong> <strong>Zaragoza, Spain, from July 3 to 5, 2019</strong>.</strong>
Electroanalysis, 2017
A potentiometric thin‐film sensor to detect CO2 in a wide range (2–100 %) has been developed. The... more A potentiometric thin‐film sensor to detect CO2 in a wide range (2–100 %) has been developed. The system has been fabricated depositing a reference electrode of Pt, a solid electrolyte of YSZ (Yttria‐stabilized Zirconia), a sensing phase made of Li2CO3 and a working electrode of Au via Physical Vapor Deposition (PVD). Characterization of the different elements has provided the optimal fabrication parameters and the system response for CO2 concentrations can be measured from 2 to 100 % at 450 °C. The sensor behaves as a non‐Nerstian system and slightly deviates from a linear response with the logarithm of CO2 until the CO2 concentration reaches the 30 %. Higher CO2 amounts make the response divert more from the Nernst law but give a stable and reproducible response to CO2 in a wide range of concentrations. Based on these promising results the recovery time, stability, repeatability and selectivity of the sensor have been measured. The performance showed by the thin film sensor proves...
Sensors and Actuators B: Chemical, 2019
Authors' biographies Laura Parellada Monreal received her BS degree in Physics from the Universit... more Authors' biographies Laura Parellada Monreal received her BS degree in Physics from the University of Barcelona in 2013 and her MSc degree in Nanophysics and Nanostructures from the University Joseph Fourier in Grenoble (France) in 2015. Since 2016, she is a PhD student in the Micro and Nano Systems Research Line. Her PhD project is focused on semiconductor materials nanostructured by laser techniques for gas sensing on environmental applications. Sandro Gherardi received his Bachelor's Degree in Tecnologie Fisiche Innovative (TFI) in 2002, with a thesis addressed to the study of the electrical response to various pollutant gases, based on nanostructured gas sensors and performed at the Sensors and
Proceedings, 2019
The performance of a metal oxide gas sensor can be affected by different parameters as the fabric... more The performance of a metal oxide gas sensor can be affected by different parameters as the fabrication process of the sensitive layer or the post-annealing treatment. [...]
Proceedings, 2019
Direct Laser Interference Patterning (DLIP) technique has been used to generate a line pattern on... more Direct Laser Interference Patterning (DLIP) technique has been used to generate a line pattern on the surface of WO3 thin films, due to the interference of two coherent laser beams, modifying its surface morphology and physical properties. Gas sensing devices based on WO3 thin films annealed at 600 °C and nanostructured by DLIP have been fabricated and compared to samples simply annealed at the same temperature. The sensors processed by DLIP present a great enhancement on the response in NO2 atmospheres indicating possible modifications on the composition, aside from the morphological one.
Smart Sensors, Actuators, and MEMS VIII, 2017
ZnO thin film on alumina has been deposited by RF sputtering and processed by two dimensional dir... more ZnO thin film on alumina has been deposited by RF sputtering and processed by two dimensional direct laser interference patterning (DLIP) using a nanosecond laser (λ=355nm). The thermodynamic and structural properties have been investigated. Morphological characterization has shown a line-pattern structure with small alterations depending on the fluence of the laser (85 mJ/cm2 or 165 mJ/cm2). In order to understand these modifications, a simulation has been carried out to model the transient temperature during the DLIP to study the temperature reached by the ZnO surface for the different fluences. Moreover, a comparison with a non-interference energy distribution pulse is also simulated to corroborate the model. For samples processed by DLIP, a thermal annealing effect has been noticed when temperatures at the surface are between 1000K and 1800K. Due to the slow cooling process, a possible recrystallization of the material similar to a thermal treatment is obtained. For temperatures close or higher than 1800K, the material starts to ablate.
Proceedings, 2017
In this work, the fabrication of a SPR (Surface Plasmon Resonance)-grating coupler using Laser In... more In this work, the fabrication of a SPR (Surface Plasmon Resonance)-grating coupler using Laser Interference Lithography (LIL) has been investigated, giving rise to large area diffraction gratings on a 100 nm-thick gold film. The period of the diffraction grating is Λ = 500 nm. The SPR sensor has been tested towards several liquids showing a maximum sensitivity of S = 390 nm/RIU.
Proceedings of the 8th Spanish Conference on Electron Devices, CDE'2011, 2011
ABSTRACT T In this work nickel oxide (NiO) thin films have been tested against low concentrations... more ABSTRACT T In this work nickel oxide (NiO) thin films have been tested against low concentrations of formaldehyde (HCHO). NiO thin films were deposited on alumina substrates by RF reactive magnetron sputtering in a mixed atmosphere of argon and oxygen. A Pt heating resistor was deposited on the reverse side for an accurate control of the operating temperature. Samples were annealed in synthetic air for 4 hours at 700ºC in order to stabilize their microstructure. Two different thicknesses (150 and 300 nm) were deposited in order to study the influence of this parameter on both the microstructure and sensor response. Both XRD analysis and FEG-SEM images show a smaller grain size for the 150 nm-thick samples. The best operating temperature was established at 340 and 300 ºC for 150 and 300 nm-thick samples respectively. A higher sensitivity was obtained for the samples of lower thickness for a set of HCHO concentrations ranging from 5 to 20 ppm. Moreover, the repeatability of the experiments was tested for the most sensitive samples.
2013 Spanish Conference on Electron Devices, 2013
ABSTRACT In this paper the direct growth of ZnO nanostructures onto a sensing device for benzene ... more ABSTRACT In this paper the direct growth of ZnO nanostructures onto a sensing device for benzene gas sensing is presented. This sensor consists in an alumina substrate with platinum interdigitated microelectrodes and a Pt heater. The nanostructure growth process is based on a vapor-liquid-solid method starting from a RF sputtered Zn thin film.
Procedia Engineering, 2014
The aim of this work is to develop an easy-to-manufacture and highly-sensitive conductometric mic... more The aim of this work is to develop an easy-to-manufacture and highly-sensitive conductometric microsensor for indoor air quality (IAQ) monitoring. The sensing material is nanostructured ZnO on Pt electrodes. A Pt heater surrounds the ZnO, so the whole sensor is fabricated on one side of a 2,5x2,5 mm 2 alumina substrate. ZnO nanostructures are grown in-situ over the electrodes, using the Vapour-Solid (VS) approach. The samples have been tested under different concentrations of benzene, formaldehyde and nitrogen dioxide, showing significant response to low concentrations of the three gases.
Proceedings of the 8th Spanish Conference on Electron Devices, CDE'2011, 2011
Yttrium stabilized zirconium oxide (YSZ) is a very interesting material for industrial applicatio... more Yttrium stabilized zirconium oxide (YSZ) is a very interesting material for industrial applications such as fuel cells or electrochemical sensors. One of the approaches to improve the performance of these devices is to reduce the YSZ thickness. In this work, the fabrication process and structural properties of RF sputtered YSZ thin films onto alumina substrates are analyzed. Under the deposition
2014 XI Tecnologias Aplicadas a la Ensenanza de la Electronica (Technologies Applied to Electronics Teaching) (TAEE), 2014
Evaluation methods must optimize the student learning process. In courses of the nature of Digita... more Evaluation methods must optimize the student learning process. In courses of the nature of Digital Systems, the practical application of the acquired knowledge is as important as the theoretical knowledge itself. On the other hand, the development of professional skills during the learning process is a key for the integral formation of the students.
CrystEngComm, 2015
Li2CO3 sputtered films of 300 nm have been subjected to physical and electrochemical characteriza... more Li2CO3 sputtered films of 300 nm have been subjected to physical and electrochemical characterization methods to analyze the influence of annealing treatments at 600 °C for 2 h, 6 h, 12 h and 18 h on the microstructure, surface and conductivity.
Thin Solid Films, 2013
ABSTRACT This work reviews the up-to-now developed formaldehyde conductometric gas sensors. First... more ABSTRACT This work reviews the up-to-now developed formaldehyde conductometric gas sensors. First, the different methods employed to fabricate the sensing films are explained. They are divided into three groups: thick film and thin film technology based sensors and nanostructured materials. Then, the sensing characteristics of the different devices are presented focusing on the strategies employed to enhance their response. It is shown that regardless of the fabrication technology, ZnO or In 2 O 3 is within the materials with the highest sensitivity to this gas. Furthermore, the sensitivity of ZnO can be improved by doping with proper materials such as Mn, Sn or CdO. Moreover, the effect of the grain size of conventional (thick or thin) films and diam-eter of the nanofibers is discussed in this review. Furthermore, the results show that nanowire-based sensors can be employed for low temperature detection with fast response. However, despite the high sensitivity reported with some devices, further research is needed to deal with the influence of operating conditions, such as interferents, humidity and long-term stability.
Thin Solid Films, 2011
The aim of the present work is to test the performance of nickel oxide (NiO) thin films to low co... more The aim of the present work is to test the performance of nickel oxide (NiO) thin films to low concentrations of formaldehyde (HCHO). NiO thin films were deposited on alumina substrates by RF reactive magnetron sputtering in a mixed atmosphere of argon and oxygen. A Pt heating resistor was deposited on the reverse side for an accurate control of the
Sensors and Actuators B: Chemical, 2006
BaTiO 3 -CuO films are obtained by RF magnetron sputtering on Si and alumina substrates and annea... more BaTiO 3 -CuO films are obtained by RF magnetron sputtering on Si and alumina substrates and annealed at different temperatures in order to check their structural characteristics and also to test their electrical behaviour by means of impedance measurements under different CO 2 concentrations (0-2000 ppm). Pt and Ag are tested as electrode materials and the influence of Ag as surface and multilayer additive for sensor response enhancement is also studied.
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Papers by Gemma García Mandayo