Carlos García Núñez

Carlos García Núñez
University of the West of Scotland | UWS · Computing, Engineering and Physical Sciences

PhD in Physics: Advanced Materials and Nanotechnology

About

70
Publications
8,787
Reads
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1,238
Citations
Citations since 2016
39 Research Items
1182 Citations
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2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
Introduction
My current research comprises synthesis and characterization of new advanced materials such as semiconductor nanostructures (nanowires, graphene, etc.) and thin films for different applications, including optoelectronics, photovoltaics, sensing, electronic-skin, and energy storage applications. In addition, I research high-performance techniques to integrate nanostructures over large-areas through contact-printing, dielectrophoresis, and optoelectronic tweezing techniques.
Additional affiliations
October 2015 - present
University of Glasgow
Position
  • Postdoctoral Research Assistant
Description
  • Development of flexible/stretchable electronics based on semiconductor nanowires and two-dimensional materials such as graphene for electronic-skin applications.
January 2015 - June 2015
Universidad Autónoma de Madrid
Position
  • Laboratory Assistant
Description
  • Electric Circuits. Boston University program, Universidad Autónoma de Madrid.
October 2014 - January 2015
Universidad Autónoma de Madrid
Position
  • Laboratory Assistant
Description
  • Digital Electric Circuits. 2nd year of informatics program, Universidad Autónoma de Madrid)

Publications

Publications (70)
Article
Full-text available
Mechanical manipulation of nanowires (NWs) for their integration in electronics is still problematic because of their reduced dimensions, risking to produce mechanical damage to the NW structure and electronic properties during the assembly process. In this regard, contactless NW manipulation based methods using non-uniform electric fields, like di...
Article
Full-text available
Energy autonomy is key to the next generation portable and wearable systems for several applications. Among these, the electronic-skin or e-skin is currently a matter of intensive investigations due to its wider applicability in areas, ranging from robotics to digital health, fashion and internet of things (IoT). The high density of multiple types...
Article
Full-text available
Energy autonomy is critical for wearable and portable systems and to this end storage devices with high‐energy density are needed. This work presents high‐energy density flexible supercapacitors (SCs), showing three times the energy density than similar type of SCs reported in the literature. The graphene–graphite polyurethane (GPU) composite based...
Book
Advanced nanostructured materials such as organic and inorganic micro/nanostructures are excellent building blocks for electronics, optoelectronics, sensing and photovoltaics because of their high crystallinity, long aspect ratio, high surface-to-volume ratio and low dimensionality. However, their assembly over large areas and integration in functi...
Article
Full-text available
In this work, we have developed a contact-printing system to efficiently transfer the bottom-up and top-down semiconductor nanowires (NWs), preserving their as-grown features with a good control over their electronic properties. In the close-loop configuration, the printing system is controlled with parameters such as contact pressure and sliding s...
Article
This paper presents a flexible ultraviolet (UV) photodetector (PD) system based on zinc oxide (ZnO) nanowires (NWs) for wearable UV dosimetry. High-crystal quality ZnO NWs have been synthesized by chemical vapour transport technique on c-plane sapphire substrates, and thereafter, transferred and aligned at pre-defined locations on a flexible substr...
Article
Full-text available
A flexible three-dimensional porous graphene foam-based supercapacitor (GFSC) is presented here for energy storage applications. With a novel layered structure of highly conductive electrodes (graphene-Ag conductive epoxy–graphene foam), forming an electrochemical double layer, the GFSC exhibits excellent electrochemical and supercapacitive perform...
Article
The successful synthesis of high crystalline quality and high aspect ratio GaAs nanowires (NWs) with a uniform diameter is needed to develop advanced applications beyond the limits established by thin film and bulk material properties. Vertically aligned GaAs NWs have been extensively grown by Ga-assisted vapour-liquid-solid (VLS) mechanism on Si(1...
Article
This work reports a temperature-assisted dip-coating method for self-assembly of silica (SiO2) micro-/nano-spheres (SPs) as monolayers over large areas (~cm2). The area over which self-assembled monolayers (SAMs) are formed can be controlled by tuning the suspension temperature (Ts), which allows precise control over meniscus shape. Furthermore, th...
Article
Full-text available
This paper presents novel Neural Nanowire Field Effect Transistors (υ-NWFETs) based hardware-implementable neural network (HNN) approach for tactile data processing in electronic skin (e-skin). The viability of Si nanowires (NWs) as the active material for υ-NWFETs in HNN is explored through modeling and demonstrated by fabricating the first device...
Article
Tactile or electronic skin is needed to provide critical haptic perception to robots and amputees, as well as in wearable electronics for health monitoring and wellness applications. Energy autonomy of skin is a critical feature that would enable better portability and longer operation times. This study shows a novel structure, consisting of a tran...
Conference Paper
Zinc nitride films can be deposited by radio frequency magnetron sputtering using a Zn target at substrate temperatures lower than 250°C. This low deposition temperature makes the material compatible with flexible substrates. The asgrown layers present a black color, polycrystalline structures, large conductivities, and large visible light absorpti...
Article
Almost all, if not all, general purpose codes for analysis of Ion Beam Analysis data have been originally developed to handle laterally homogeneous samples only. This is the case of RUMP, NDF, SIMNRA, and even of the Monte Carlo code Corteo. General-purpose codes usually include only limited support for lateral inhomogeneity. In this work, we show...
Poster
Current work shows cost-effective transfer techniques including tape-peeling and contact-printing, and their performance to assemble Si nanowires on flexible substrates
Article
Growth kinetics of GaAs nanowires (NWs) on Si(111) substrates by Ga-assisted chemical beam epitaxy is studied as a function of growth conditions such as substrate temperature (Ts), V/III flux ratio and catalyst dimension. The preparation method for Si(111) substrates is optimized in order to obtain a thin surface oxide with a thickness around 0.5 n...
Conference Paper
Full-text available
Multiband solar cells are the third generation photovoltaic devices in which an increase of the power conversion efficiency is achieved through an absorption of low energy photons while preserving a large band gap that determines the open circuit voltage. The ability to absorb photons from different solar spectrum regions is due to an intermediate...
Conference Paper
Full-text available
Electrical characterization of GaAs nanowires (NWs) grown by Ga-assisted chemical beam epitaxy (CBE) on Si(111) substrates using triethylgallium (TEGa) and tertiarybutylarsine (TBAs) is studied under illumination and dark conditions. NW crystalline structure was analyzed in-situ by reflection high energy electron diffraction (RHEED), showing only z...
Article
Although nanowires (NWs) may improve the performance of many optoelectronic devices such as light emitters and photodetectors, the mass commercialization of these devices is limited by the difficult task of finding reliable and reproducible methods to integrate the NWs on foreign substrates. This work shows the fabrication of zinc oxide NWs photode...
Article
Silanization is commonly used to form bonds between inorganic materials and biomolecules as a step in the surface preparation of solid-state biosensors. This work investigates the effects of silanization with amino-propyldiethoxymethylsilane (APDEMS) on hydroxylated sidewalls of zinc oxide (ZnO) nanowires (NWs). The surface properties and electrica...
Conference Paper
Full-text available
GaAs nanowires (NWs) growth kinetics by Ga-assisted chemical beam epitaxy on Si(111) substrates is studied as a function of the initial Ga catalyst dimensions and growth parameters such as substrate temperature and V/III flux ratio. The preparation method for substrates is optimized in order to obtain a surface oxide with a thickness around 0.5 nm,...
Conference Paper
This work describes the development of ZnO nanowire (NW) devices for ultraviolet detection and cost-effective gas sensing. A dielectrophoresis (DEP) flow cell fabricated for the integration of NWs on different substrates is presented. The system includes the possibility to set characteristic parameters such as alternating current (AC) frequency, am...
Article
Surface optical (SO) phonons were studied by Raman spectroscopy in GaAs nanowires (NWs) grown by Ga-assisted chemical beam epitaxy on oxidized Si(111) substrates. NW diameters and lengths ranging between 40 and 65 nm and between 0.3 and 1.3 μm, respectively, were observed under different growth conditions. The analysis of the Raman peak shape assoc...
Conference Paper
Applying an electric field offers a low-cost, bottom-up approach to integrating suspended dielectric metal oxide nanowires in electronic devices.
Article
This work analyzes the morphological, compositional and electrical modification of zinc nitride (Zn3N2) films through arc discharges produced by biasing a metal tip at a micrometric distance of the surface. Polycrystalline nitride layers are prepared by radio-frequency magnetron sputtering from a pure Zn target on glass substrates using N2 as worki...
Article
ZnO nanowires (NWs) with different radii (rNW) have been aligned between pre-patterned electrodes using dielectrophoresis (DEP) for the fabrication of high gain UV sensors. The DEP conditions (voltage amplitude and frequency) and electrode material, geometry and size were optimized to enhance the efficiency during the DEP process. To understand the...
Article
Metal oxide nanowire (NW) photoconductors tend to exhibit high photoconductive gains and long recovery times mainly due to surface effects. In this work, p-type CuO NWs are synthesized by direct oxidation of copper and deposited on n-type ZnO:Al electrodes by dielectrophoresis. The heterostructure is electro-optically characterized showing recovery...
Conference Paper
GaAs nanowires (NWs) were grown by Ga-assisted chemical beam epitaxy on Si(111) substrates covered by a thin oxide layer using different substrate temperatures and growth times. Ga droplet terminated NWs with hexagonal footprint and cross-section were observed by scanning electron microscopy, with diameters and lengths in the range of 40–65 nm and...
Conference Paper
Metal oxide nanowires (NWs) present high stability and excellent optical, electrical and mechanical properties. Their synthesis is cost-effective since they can be produced by means of conventional ovens using vapor phase transport or direct metal oxidation. In this work, n-type ZnO and p-type CuO NWs are deposited on pre-patterned electrodes of Al...
Conference Paper
Metal oxide nanowires are promising structures for the development of novel electronic and optoelectronic devices. In this work, we describe the synthesis of ZnO and CuO nanowires by vapor phase transport and Cu oxidation, respectively. After removal from the substrate, the nanowires are deposited on pairs of conductive electrodes previously evapor...
Article
Zinc nitride films were used as an active layer in thin film transistors to assess its performance in optoelectronic applications. Those nitride layers were grown by radio-frequency magnetron sputtering in Ar/N2 ambient using a Zn target. Bottom- and top-gate thin film transistors were fabricated by photolithography processes. Transmission measurem...
Article
Zinc nitride (Zn3N2) films were prepared by radio-frequency magnetron sputtering from a pure Zn target in a N2 ambient. Films were deposited on glass and Si(100) substrates at 298- and 473-K substrate temperatures (Ts). Ion beam analysis (IBA) techniques, spectroscopic ellipsometry (SE) and transmission spectroscopy were used to characterize the sa...
Conference Paper
Zinc oxide (ZnO) nanowires (NWs) based ultraviolet (UV) sensors have been fabricated using different assembly techniques to form functional structures, aiming at the improvement of the performance of NW-based sensors for optoelectronic applications. NWs with diameters and lengths varying between 90–870 nm and 2–20 μm, respectively, were synthesized...
Article
Zinc nitride films were prepared by radio-frequency magnetron sputtering in N2/Ar ambient using different substrates (glass and thermally-oxidized-Si) and buffer layers (low-temperature Zn3N2 and ZnO). Resonant Rutherford backscattering (RBS) allowed determining ZnxNy stoichiometry and thickness. Despite the sputtering system was operated in high v...
Article
Refractive index (n) and extinction coefficient (k) of Zn3N2 layers deposited by radio-frequency magnetron sputtering at temperatures (Ts) between 298 and 523 K were determined by spectroscopic ellipsometry. Results showed strong variations of the apparent optical constants with Ts and time attributed to surface effects. Resonant Rutherford backsca...
Conference Paper
Full-text available
Group-IV elements, when used as dopants, should be incorporated into the crystal lattice in substitutional positions. In the case of GaAs:Sn, depending on the sublattice position Sn incorporates to, it can behave either as a donor or an acceptor (amphoteric character), although Sn presents a strong tendency to incorporate into the group-III sublatt...
Conference Paper
In this work, polycrystalline zinc nitride films were prepared on Si and glass substrates by rf magnetron sputtering in N2 ambient using Zn as a target. Substrate temperature (Ts) was different for each deposition process ranging from 298 K to 523 K. Optical transmission experiments showed that the optical band gap of the resultant layers decreased...
Conference Paper
Spectroscopic ellipsometry in external reflection (ER) and total internal reflection (TIR) modes is used to characterize surface plasmon resonance in Au nanoparticles (AuNPs) deposited on Al-doped ZnO films via surface thiolation. ER ellipsometry exhibits high sensitivity to the alkanethiol layer as well as to localized surface plasmons at energies...
Conference Paper
Full-text available
This work describes the fabrication and characterization of tin doped GaAs(100) layers, grown by Chemical Beam Epitaxy (CBE). Tin, as a group-IV element, can incorporate into the GaAs crystal lattice in substitutional positions. Depending on the sublattice position, its contribution can be donor or acceptor (amphoteric character) although it presen...

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