1,720,973 research outputs found
Advanced Iontronic Nanowire Devices: Design, Fabrication and Applications.
No full textNanotechnology has revolutionized electronics by enabling the creation of nanoscale devices offering superior performance and functionalities. This breakthrough has boosted technological advancements and provided essential tools for various fields including energy generation and storage, bioelectronics and quantum technologies. Despite these remarkable achievements, conventional nanotechnological platforms that rely on electrical transport in semiconductors exhibit significant drawbacks, such as complex device fabrication processes and limitations in device functionalities due to inherent constraints in the materials used for fabrication. These limitations stem from the widely employed Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) device architecture, which necessitates a thin oxide layer to enable field-effect control over semiconductor electrical transport properties. This requirement introduces detrimental aspects such as vulnerability to dielectric breakdown and channel-to-gate leakage currents, hindering the capabilities of nanostructured semiconductors. To overcome such limitations the field of iontronics has emerged, focusing on the utilization of ion migration in electrolyte materials to enhance electronic functionality and enable novel device architectures.This Ph.D. thesis investigates the fundamental principles, fabrication techniques, and potential applications of iontronics for the development of devices based on semiconducting nanostructures. The research aims to investigate the impact of ion migration and arrangement on the electronic properties of nanoscale semiconductors. It focuses on the development of nanoscale devices with enhanced functionality, with potential applications in nanoelectronics, thermoelectrics and quantum technologies. Specifically, the development of iontronic nanowire-based devices is explored, since this class of nanostructures is of particular interest due to its technological relevance and its high aspect ratio.The outcomes of this Ph.D. research project aim to progress the field of nanodevice iontronics, highlighting the potential for advanced electronic functionalities beyond traditional electronics and focusing on the development of practical strategies for designing and fabricating iontronic nanodevices with enhanced performance. By leveraging the approach offered by iontronics, high-performance thermoelectric generators, nanoelectronic components and systems for quantum technologies are developed
Impact of counter-electrode and device architecture on the gating performance of iontronic transistors
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The Iontronic Quantum Dot
Full text linkSemiconductor quantum dots (QDs) are key building blocks for quantum technologies with applications in quantum computation, communication, and sensing. QD device architectures rooted in conventional solid-state device fabrication paradigms are grappled with complex protocols to balance ease of realization, scalability, and transport properties. Using ion gating, we demonstrate a novel paradigm of quantum device engineering, that enables the realization and control of the iontronic QD. Clear Coulomb blockade peaks and their dependence on an externally applied magnetic field are reported, together with the impact of device architecture and confinement potential on QD quality. Devices incorporating two identical iontronic QDs in series are realized, addressing the reproducibility of the approach. A novel class of zero-dimensional quantum devices, iontronic QDs, overcome the need for thin dielectric layers, facilitating single-step device fabrication. This approach holds the potential to impact the development of quantum materials and devices in the context of solid-state quantum technologies
Suspended InAs Nanowire-Based Devices for Thermal Conductivity Measurement Using the 3ω Method
No full textWe demonstrated device architectures implementing suspended InAs nanowires for thermal conductivity measurements. To this aim, we exploited a fabrication protocol involving the use of a sacrificial layer. The relatively large aspect ratio of our nanostructures combined with their low electrical resistance allows to exploit the four-probe 3ω technique to measure the thermal conductivity, inducing electrical self-heating in the nanowire at frequency ω and measuring the voltage drop across the nanostructure at frequency 3ω. In our systems, field effect modulation of the transport properties can be achieved exploiting fabricated side-gate electrodes in combination with the SiO2/Si ++ substrate acting as a back gate. Our device architectures can open new routes to the all-electrical investigation of thermal parameters in III-V semiconductor nanowires, with a potential impact on thermoelectric applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Thermoelectric Effects in Nanowire Quantum Dots
No full textIn this thesis we worked with InAs/InP heterostructured semiconductor nanowires, with the aim to explore thermoelectric effects in strongly-confined quantum dots (QDs). Fabrication procedure is described and a complete analysis of the experimental data on the thermoelectric response of the nanoscale QDs is provided, showing that Seebeck coefficient modulation in our system is possible even in temperature regimes higher than previously reported
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