16 research outputs found

    Scalable techniques for graphene on glass

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    The combination of unique properties -high electrical mobility, thermal conductivity, transparency and mechanical flexibility- make graphene promising for a wide variety of applications, including transparent electrodes, flexible displays, touch-screens and wearables. One of the main reasons that prevent its widespread use is the difficulty to maintain all of the previously mentioned properties when grown using industrial grade techniques. The most widely used technique for growing graphene on a large scale is Chemical Vapor Deposition (CVD), where graphene is, typically, first deposited on a Cu catalyst foil and then transferred to a target substrate using additional sacrificial materials (polymers). The transfer is time-consuming and can worsen the graphene properties and its quality. For instance, residues from transfer materials can alter the doping level. This thesis has investigated the direct growth, dry transfer and doping control of graphene on glass substrates, suggesting new methods and designs to improve the use of such substrates in devices, with a particular focus on optical applications where preserving the transparency is often required. The thesis demonstrates direct growth of graphene on the desired target substrate using two techniques without any transfer step. In the first technique, graphene was grown on large patterned areas by using catalytic ultra-thin metal films (UTMFs) made of Ni, with thicknesses ranging from 5 to 50 nanometers. The dewetting of Ni UTMF when exposed to high growth temperatures allows graphene to deposit on the glass surface while the metal film is breaking and is retracted. In the second technique, graphene was grown on large areas covered by Cu nanoparticles, which can be arranged into different patterns and with surface densities. Tuning the Cu density by dip-coating and evaporation techniques and the possibility of etching the Cu afterwards allow the growth of flat graphene networks, but also of graphene assembled into three-dimensional shapes with high effective surface area, which opens up more potential applications. CVD of graphene on Cu foil is a powerful growth technique, but its transfer is still a challenge. This thesis has demonstrated a successful dry transfer technique for graphene on glass substrates using interfacial polyimide layers, which is faster, easier and more scalable while preserving the electrical transport and optical properties. The doping of graphene through the substrate surface or the additional top layers is not always easy to control. If not properly carried out, it can degrade the graphene properties, even when the previous growth and transfer steps have been successfully performed. This thesis has investigated a doping control post-processing technique, called “thermal poling” of glass, to induce the charge at the surface of the glass substrate and thus modify the electronic carrier density of graphene. The charge in the glass originates from the displacement of ions that become mobile at temperatures above 100ºC and when subjected to an electrical voltage of up to few kV. The corresponding stable and “frozen-in” electric field is responsible for the doping of graphene. The results of this thesis widen the range of graphene applications where largescale growth, practical transfer and doping control are required. At the same time, the thesis also opens new research avenues, especially to improve further the graphene quality when incorporated in devices.Esta tesis ha investigado el crecimiento directo, transferencia por vía seca y el control de dopaje del grafeno en vidrio, sugiriendo nuevos métodos y diseños para mejorar el uso de estos substratos en dispositivos, especialmente para aquellos con aplicaciones ópticas donde es necesaria una elevada transparencia. La tesis demuestra el crecimiento directo de grafeno en el substrato final deseado,usando para ello dos técnicas diferentes que evitan cualquier etapa de transferencia. En la primera técnica, el grafeno se ha crecido en áreas grandes y prediseñadas usando como catalizador láminas ultra-finas (UTMFs) de níquel con espesores comprendidos entre 5 y 50 nanómetros. Cuando estas láminas metálicas son expuestas a las temperaturas elevadas necesarias para crecer el grafeno ocurre el fenómeno de dewetting, en el cuál la lámina se rompe y el metal se retrae, lo que conlleva que el grafeno que ha crecido en el níquel se deposite en la superficie del vidrio. En la segunda técnica, el grafeno se ha crecido sobre nanopartículas de iv cobre que han sido depositadas previamente en vidrio con diferentes estructuras y densidad superficial. La variación de densidades obtenidas en las nanopartículas de cobre durante su deposición en vidrio, mediante técnicas de inmersión y evaporación,y la elliminación posterior del cobre permiten el crecimiento de grafeno en forma de red plana, pero también en estructuras tridimensionales con mayores áreas superficiales, lo que incrementa las posibles aplicaciones futuras. El crecimiento de grafeno mediante CVD en una lámina de cobre es la técnica más prometedora a nivel industrial, pero su transferencia desde el metal hasta el substrato final es aún cuestionable y supone un reto para lograr la completa implementación de esta tecnología. Esta tesis demuestra la capacidad de una técnica por vía seca y escalable a nivel industrial, para transferir grafeno de manera efectiva rápida y sencilla en substratos de vidrio, utilizando poliamida como material intermedio entre ambos y preservando las propiedades eléctricas y ópticas del grafeno. El dopaje de grafeno que se adquiere bien por la superficie del substrato final o por la contribución de capas depositadas encima, es difícil de controlar y puede conllevar a la degradación total de las propiedades elétricas del material, incluso cuando las etapas de síntesis y transferencias se han llevado a cabo de manera correcta. Esta tesis ha investigado la aplicación de una técnica para controlar el dopaje del grafeno a posteriori, es decir, una vez que ha sido depositado en el vidrio. Esta técnica se conoce como polarización térmica del vidrio y consiste en la inducción de una carga en la superficie del vidrio que provocará una modificación controlada del dopaje del grafeno. Esta carga superficial del vidrio se origina por el desplazamiento de iones provenientes de aditivos del vidrio, que comienzan a moverse a temperaturas superiores a 100ºC y cuando se aplica un voltaje externo de kV. Este proceso da lugar a un campo eléctrico muy estable, confinado y "congelado" dentro del vidrio a temperatura ambiente que será el responsable de la modificación del dopaje del grafeno. Los resultados de esta tesis amplían el rango de aplicaciones del grafeno donde es necesarios su crecimiento a gran escala, un método de transferencia efectivo y práctico y un control sobre su dopaje final. Del mismo modo, esta tesis también abre nuevas vías de desarrollo e investigación, especialmente para mejorar la calidad del grafeno cuándo éste es incorporado finalmente en dispositivos

    Scalable techniques for graphene on glass

    Get PDF
    The combination of unique properties -high electrical mobility, thermal conductivity, transparency and mechanical flexibility- make graphene promising for a wide variety of applications, including transparent electrodes, flexible displays, touch-screens and wearables. One of the main reasons that prevent its widespread use is the difficulty to maintain all of the previously mentioned properties when grown using industrial grade techniques. The most widely used technique for growing graphene on a large scale is Chemical Vapor Deposition (CVD), where graphene is, typically, first deposited on a Cu catalyst foil and then transferred to a target substrate using additional sacrificial materials (polymers). The transfer is time-consuming and can worsen the graphene properties and its quality. For instance, residues from transfer materials can alter the doping level. This thesis has investigated the direct growth, dry transfer and doping control of graphene on glass substrates, suggesting new methods and designs to improve the use of such substrates in devices, with a particular focus on optical applications where preserving the transparency is often required. The thesis demonstrates direct growth of graphene on the desired target substrate using two techniques without any transfer step. In the first technique, graphene was grown on large patterned areas by using catalytic ultra-thin metal films (UTMFs) made of Ni, with thicknesses ranging from 5 to 50 nanometers. The dewetting of Ni UTMF when exposed to high growth temperatures allows graphene to deposit on the glass surface while the metal film is breaking and is retracted. In the second technique, graphene was grown on large areas covered by Cu nanoparticles, which can be arranged into different patterns and with surface densities. Tuning the Cu density by dip-coating and evaporation techniques and the possibility of etching the Cu afterwards allow the growth of flat graphene networks, but also of graphene assembled into three-dimensional shapes with high effective surface area, which opens up more potential applications. CVD of graphene on Cu foil is a powerful growth technique, but its transfer is still a challenge. This thesis has demonstrated a successful dry transfer technique for graphene on glass substrates using interfacial polyimide layers, which is faster, easier and more scalable while preserving the electrical transport and optical properties. The doping of graphene through the substrate surface or the additional top layers is not always easy to control. If not properly carried out, it can degrade the graphene properties, even when the previous growth and transfer steps have been successfully performed. This thesis has investigated a doping control post-processing technique, called “thermal poling” of glass, to induce the charge at the surface of the glass substrate and thus modify the electronic carrier density of graphene. The charge in the glass originates from the displacement of ions that become mobile at temperatures above 100ºC and when subjected to an electrical voltage of up to few kV. The corresponding stable and “frozen-in” electric field is responsible for the doping of graphene. The results of this thesis widen the range of graphene applications where largescale growth, practical transfer and doping control are required. At the same time, the thesis also opens new research avenues, especially to improve further the graphene quality when incorporated in devices.Esta tesis ha investigado el crecimiento directo, transferencia por vía seca y el control de dopaje del grafeno en vidrio, sugiriendo nuevos métodos y diseños para mejorar el uso de estos substratos en dispositivos, especialmente para aquellos con aplicaciones ópticas donde es necesaria una elevada transparencia. La tesis demuestra el crecimiento directo de grafeno en el substrato final deseado,usando para ello dos técnicas diferentes que evitan cualquier etapa de transferencia. En la primera técnica, el grafeno se ha crecido en áreas grandes y prediseñadas usando como catalizador láminas ultra-finas (UTMFs) de níquel con espesores comprendidos entre 5 y 50 nanómetros. Cuando estas láminas metálicas son expuestas a las temperaturas elevadas necesarias para crecer el grafeno ocurre el fenómeno de dewetting, en el cuál la lámina se rompe y el metal se retrae, lo que conlleva que el grafeno que ha crecido en el níquel se deposite en la superficie del vidrio. En la segunda técnica, el grafeno se ha crecido sobre nanopartículas de iv cobre que han sido depositadas previamente en vidrio con diferentes estructuras y densidad superficial. La variación de densidades obtenidas en las nanopartículas de cobre durante su deposición en vidrio, mediante técnicas de inmersión y evaporación,y la elliminación posterior del cobre permiten el crecimiento de grafeno en forma de red plana, pero también en estructuras tridimensionales con mayores áreas superficiales, lo que incrementa las posibles aplicaciones futuras. El crecimiento de grafeno mediante CVD en una lámina de cobre es la técnica más prometedora a nivel industrial, pero su transferencia desde el metal hasta el substrato final es aún cuestionable y supone un reto para lograr la completa implementación de esta tecnología. Esta tesis demuestra la capacidad de una técnica por vía seca y escalable a nivel industrial, para transferir grafeno de manera efectiva rápida y sencilla en substratos de vidrio, utilizando poliamida como material intermedio entre ambos y preservando las propiedades eléctricas y ópticas del grafeno. El dopaje de grafeno que se adquiere bien por la superficie del substrato final o por la contribución de capas depositadas encima, es difícil de controlar y puede conllevar a la degradación total de las propiedades elétricas del material, incluso cuando las etapas de síntesis y transferencias se han llevado a cabo de manera correcta. Esta tesis ha investigado la aplicación de una técnica para controlar el dopaje del grafeno a posteriori, es decir, una vez que ha sido depositado en el vidrio. Esta técnica se conoce como polarización térmica del vidrio y consiste en la inducción de una carga en la superficie del vidrio que provocará una modificación controlada del dopaje del grafeno. Esta carga superficial del vidrio se origina por el desplazamiento de iones provenientes de aditivos del vidrio, que comienzan a moverse a temperaturas superiores a 100ºC y cuando se aplica un voltaje externo de kV. Este proceso da lugar a un campo eléctrico muy estable, confinado y "congelado" dentro del vidrio a temperatura ambiente que será el responsable de la modificación del dopaje del grafeno. Los resultados de esta tesis amplían el rango de aplicaciones del grafeno donde es necesarios su crecimiento a gran escala, un método de transferencia efectivo y práctico y un control sobre su dopaje final. Del mismo modo, esta tesis también abre nuevas vías de desarrollo e investigación, especialmente para mejorar la calidad del grafeno cuándo éste es incorporado finalmente en dispositivos.Postprint (published version

    Low temperature direct growth of graphene patterns on flexible glass substrates catalysed by a sacrificial ultrathin Ni film

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    Direct deposition of graphene on substrates would avoid costly, time consuming and defect inducing transfer techniques. In this paper we used ultrathin films of Ni, with thickness ranging from 5 to 50 nm, as a catalytic surface on glass to seed and promote chemical vapor deposition (CVD) of graphene. Different regimes and dynamics were studied for various parameters including temperature and reaction time. When a critical temperature (700 °C) was reached, Ni films retracted and holes formed that are open to the glass surface, where graphene deposited. After CVD, the residual Ni could be etched away and the glass substrate with graphene regained maximum transparency (>90%). The fact that we could achieve low growth temperatures indicates the potential of the technique to widen the range of substrate materials over which graphene can be directly deposited. We demonstrated this by depositing graphene patterns on ultrathin, 100 μm thick, sheet of glass with low strain point (670 °C), particularly suitable for flexible electronic and optoelectronic devices.Peer ReviewedPostprint (published version

    Psychometric Properties of the Spanish Version of theWork Group Emotional Intelligence Profile Short Version (WEIP-S) in a Sample of Spanish Federated Coaches.

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    Emotional intelligence has been a topic of great interest to researchers in many different areas as it is associated with mental, psychosomatic, and physical health. In the sports context, it is a significant variable that can play an important role in improving the team’s performance. Although there are numerous tools to assess emotional intelligence, few of them have been validated explicitly in a sports sample, and even fewer have had coaches as a target population. Therefore, this study aimed to validate the Spanish version of the work group emotional intelligence profile short version (WEIP-S) in a sample of Spanish federated coaches. The results confirm that this instrument presents good psychometric properties to measure the emotional intelligence of sports coaches. The original four-factor model (awareness of one’s own emotions, management of one’s own emotions, awareness of others’ emotions, and management of others’ emotions) shows good reliability and convergent validity for all four factors except for the management of one’s own emotions. These findings suggest that it is possible to measure the emotional intelligence of coaches and offer the opportunity to continue investigating the relevance of constructing specific scales to measure this construct in the sports context.post-print363 K

    Validation of the Spanish Version of the Work Group Emotional Intelligence Profile Short Version (WEIP-S) in the Sports Context.

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    Emotional intelligence (EI) is related to better performance in sports. To measure this construct, many tools have been developed and validated in the sports context. However, these tools are based on an individual’s ability to manage their own emotions, but do not consider the emotions of the rest of the team (teammates, coaches, etc.). In this regard, the Workgroup Emotional Intelligence Profile short version (WEIP-S) is a self-reported measure designed to measure the EI of individuals who are part of a team. The aim of this study was to validate the WEIP-S structure to measure EI in the sports context, and to analyze the psychometric properties of this tool in the sample in terms of validity and reliability. A cross-sectional study was conducted among 273 athletes to examine the reliability, factor structure, and evidence of validity (convergent, discriminant, nomological, and concurrent) of the WEIP-S. Confirmatory factor analysis showed that the original four-factor structure is the most appropriate for the sports context. Composite reliability was adequate for all factors except management of one’s own emotions, which also showed poor convergent validity. Evidence of convergent, discriminant, and nomological validity are discussed. This study represents an advance in the use of specific scales to measure EI in the sports context.post-print1021 K

    Direct growth of 2D and 3D graphene nano-structures over large glass substrates by tuning a sacrificial Cu-template layer

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    We demonstrate direct growth of two-dimensional (2D) and three-dimensional (3D) graphene structures on glass substrates. By starting from catalytic copper nanoparticles of different densities and using chemical vapour deposition (CVD) techniques, different 2D and 3D morphologies can be obtained, including graphene sponge-like, nano-ball and conformal graphene structures. More important, we show that the initial copper template can be completely removed via sublimation during CVD and, if need be, subsequent metal etching. This allows optical transmissions close to the bare substrate, which, combined with electrical conductivity make the proposed technique very attractive for creating graphene with high surface to volume ratio for a wide variety of applications, including antiglare display screens, solar cells, light-emitting diodes, gas and biological plasmonic sensors.Peer ReviewedPostprint (author's final draft

    Relación entre inteligencia emocional y ansiedad en un club de fútbol sala de Madrid.

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    Diversos estudios sugieren que la Inteligencia Emocional en deportistas se relaciona con el rendimiento deportivo y, a su vez, éste se ve perjudicado cuando los deportistas experimentan emociones negativas (e.g, ansiedad) que no son gestionadas adecuadamente. Sin embargo, se necesitan estudios que analicen si esta relación ocurre en todos los niveles deportivos. El objetivo del presente estudio es analizar si existen diferencias en la inteligencia emocional (IE) y los niveles de ansiedad rasgo y estado (A/R y A/E) de jugadores de fútbol sala en función de su nivel deportivo. Para ello, se contó con una muestra de 48 jugadores de fútbol sala de todas las categorías juveniles a los que se les administró los cuestionarios TMMS-24 y STAI. Los resultados obtenidos muestran diferencias significativas en Atención Emocional (AE), A/R y A/E entre los diferentes niveles deportivos. Además, los niveles de A/R se relacionaron con todas las dimensiones de IE, mientras que la A/E únicamente se relacionó con la dimensión de AE.post-print117 K

    Dry transfer of graphene to dielectrics and flexible substrates using polyimide as a transparent and stable intermediate layer

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    We demonstrate the direct transfer of graphene from Cu foil to glass and flexible substrates such as PET, using polyimide (PI) mixed with an aminosilane (3-aminopropyltrimethoxysilane) or only PI, respectively, as intermediate layer. We probe the scalability and roll-to-roll processing of this technique by using two different equipment: hot press and a laminator. High quality, clean and continuous areas of graphene monolayer can be transferred with the advantage of Cu recycling for future growth catalyst as it is peeled-off mechanically from the substrate/PI/graphene structure. More important are the high transparency of the samples together with the electron doping achieved (n<sub>S</sub>= 0.21 to 4 x 10<sup>13</sup> cm<sup>-2</sup>), as the performing graphene face is not in direct contact with PMMA, PI or other materials, and the high mobility (µ<sub>H</sub> up to 1250 cm<sup>2</sup>/Vcenterdots). Stability of the structure in terms of sheet resistance (R<sub>S</sub>) at high temperatures, bending cycles and water immersion make this technique promising for future applications and implementation at the large scale.Postprint (author's final draft

    Non-productive angiogenesis disassembles Aß plaque-associated blood vessels

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    The human Alzheimer’s disease (AD) brain accumulates angiogenic markers but paradoxically, the cerebral microvasculature is reduced around Aß plaques. Here we demonstrate that angiogenesis is started near Aß plaques in both AD mouse models and human AD samples. However, endothelial cells express the molecular signature of non-productive angiogenesis (NPA) and accumulate, around Aß plaques, a tip cell marker and IB4 reactive vascular anomalies with reduced NOTCH activity. Notably, NPA induction by endothelial loss of presenilin, whose mutations cause familial AD and which activity has been shown to decrease with age, produced a similar vascular phenotype in the absence of Aß pathology. We also show that Aß plaque-associated NPA locally disassembles blood vessels, leaving behind vascular scars, and that microglial phagocytosis contributes to the local loss of endothelial cells. These results define the role of NPA and microglia in local blood vessel disassembly and highlight the vascular component of presenilin loss of function in AD

    Scalable techniques for graphene on glass

    No full text
    The combination of unique properties -high electrical mobility, thermal conductivity, transparency and mechanical flexibility- make graphene promising for a wide variety of applications, including transparent electrodes, flexible displays, touch-screens and wearables. One of the main reasons that prevent its widespread use is the difficulty to maintain all of the previously mentioned properties when grown using industrial grade techniques. The most widely used technique for growing graphene on a large scale is Chemical Vapor Deposition (CVD), where graphene is, typically, first deposited on a Cu catalyst foil and then transferred to a target substrate using additional sacrificial materials (polymers). The transfer is time-consuming and can worsen the graphene properties and its quality. For instance, residues from transfer materials can alter the doping level. This thesis has investigated the direct growth, dry transfer and doping control of graphene on glass substrates, suggesting new methods and designs to improve the use of such substrates in devices, with a particular focus on optical applications where preserving the transparency is often required. The thesis demonstrates direct growth of graphene on the desired target substrate using two techniques without any transfer step. In the first technique, graphene was grown on large patterned areas by using catalytic ultra-thin metal films (UTMFs) made of Ni, with thicknesses ranging from 5 to 50 nanometers. The dewetting of Ni UTMF when exposed to high growth temperatures allows graphene to deposit on the glass surface while the metal film is breaking and is retracted. In the second technique, graphene was grown on large areas covered by Cu nanoparticles, which can be arranged into different patterns and with surface densities. Tuning the Cu density by dip-coating and evaporation techniques and the possibility of etching the Cu afterwards allow the growth of flat graphene networks, but also of graphene assembled into three-dimensional shapes with high effective surface area, which opens up more potential applications. CVD of graphene on Cu foil is a powerful growth technique, but its transfer is still a challenge. This thesis has demonstrated a successful dry transfer technique for graphene on glass substrates using interfacial polyimide layers, which is faster, easier and more scalable while preserving the electrical transport and optical properties. The doping of graphene through the substrate surface or the additional top layers is not always easy to control. If not properly carried out, it can degrade the graphene properties, even when the previous growth and transfer steps have been successfully performed. This thesis has investigated a doping control post-processing technique, called “thermal poling” of glass, to induce the charge at the surface of the glass substrate and thus modify the electronic carrier density of graphene. The charge in the glass originates from the displacement of ions that become mobile at temperatures above 100ºC and when subjected to an electrical voltage of up to few kV. The corresponding stable and “frozen-in” electric field is responsible for the doping of graphene. The results of this thesis widen the range of graphene applications where largescale growth, practical transfer and doping control are required. At the same time, the thesis also opens new research avenues, especially to improve further the graphene quality when incorporated in devices.Esta tesis ha investigado el crecimiento directo, transferencia por vía seca y el control de dopaje del grafeno en vidrio, sugiriendo nuevos métodos y diseños para mejorar el uso de estos substratos en dispositivos, especialmente para aquellos con aplicaciones ópticas donde es necesaria una elevada transparencia. La tesis demuestra el crecimiento directo de grafeno en el substrato final deseado,usando para ello dos técnicas diferentes que evitan cualquier etapa de transferencia. En la primera técnica, el grafeno se ha crecido en áreas grandes y prediseñadas usando como catalizador láminas ultra-finas (UTMFs) de níquel con espesores comprendidos entre 5 y 50 nanómetros. Cuando estas láminas metálicas son expuestas a las temperaturas elevadas necesarias para crecer el grafeno ocurre el fenómeno de dewetting, en el cuál la lámina se rompe y el metal se retrae, lo que conlleva que el grafeno que ha crecido en el níquel se deposite en la superficie del vidrio. En la segunda técnica, el grafeno se ha crecido sobre nanopartículas de iv cobre que han sido depositadas previamente en vidrio con diferentes estructuras y densidad superficial. La variación de densidades obtenidas en las nanopartículas de cobre durante su deposición en vidrio, mediante técnicas de inmersión y evaporación,y la elliminación posterior del cobre permiten el crecimiento de grafeno en forma de red plana, pero también en estructuras tridimensionales con mayores áreas superficiales, lo que incrementa las posibles aplicaciones futuras. El crecimiento de grafeno mediante CVD en una lámina de cobre es la técnica más prometedora a nivel industrial, pero su transferencia desde el metal hasta el substrato final es aún cuestionable y supone un reto para lograr la completa implementación de esta tecnología. Esta tesis demuestra la capacidad de una técnica por vía seca y escalable a nivel industrial, para transferir grafeno de manera efectiva rápida y sencilla en substratos de vidrio, utilizando poliamida como material intermedio entre ambos y preservando las propiedades eléctricas y ópticas del grafeno. El dopaje de grafeno que se adquiere bien por la superficie del substrato final o por la contribución de capas depositadas encima, es difícil de controlar y puede conllevar a la degradación total de las propiedades elétricas del material, incluso cuando las etapas de síntesis y transferencias se han llevado a cabo de manera correcta. Esta tesis ha investigado la aplicación de una técnica para controlar el dopaje del grafeno a posteriori, es decir, una vez que ha sido depositado en el vidrio. Esta técnica se conoce como polarización térmica del vidrio y consiste en la inducción de una carga en la superficie del vidrio que provocará una modificación controlada del dopaje del grafeno. Esta carga superficial del vidrio se origina por el desplazamiento de iones provenientes de aditivos del vidrio, que comienzan a moverse a temperaturas superiores a 100ºC y cuando se aplica un voltaje externo de kV. Este proceso da lugar a un campo eléctrico muy estable, confinado y "congelado" dentro del vidrio a temperatura ambiente que será el responsable de la modificación del dopaje del grafeno. Los resultados de esta tesis amplían el rango de aplicaciones del grafeno donde es necesarios su crecimiento a gran escala, un método de transferencia efectivo y práctico y un control sobre su dopaje final. Del mismo modo, esta tesis también abre nuevas vías de desarrollo e investigación, especialmente para mejorar la calidad del grafeno cuándo éste es incorporado finalmente en dispositivos
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