35 research outputs found

    Analysis of Surface Charge Effects and Edge Fringing Capacitance in Planar GaAs and GaN Schottky Barrier Diodes

    Get PDF
    [EN]In this article, by means of a 2-D ensemble Monte Carlo simulator, the Schottky barrier diodes (SBDs) with realistic geometries based on GaAs and GaN are studied as promising devices for increasing the high-frequency performance- and power-handling capability of frequency mixers and multipliers. The nonlinearity of the capacitance–voltage (C–V) characteristic is the most important parameter for optimizing the performance of SBDs as frequencymultipliers. The small size of the diodes used for ultrahigh-frequency applications makes the value of its intrinsic capacitance to deviate from the ideal one due to fringing effects. We have observed that the value of the edge capacitancewell into reverse bias does not depend on the applied voltage. We define an edge-effect parameter beta, which, interestingly, is affected by the presence or absence of surface charges at the semiconductor–dielectric interface, sigma . Two physical models have been considered: a fixed sigma related to a surface potential Vs constant surface-charge model (CCM) and a self-consistent model in which the local value of sigma is dynamically evaluated depending on the surrounding electron density self-consistent surface-charge model (SCCM). Using the CCM, we obtain that beta depends on the depth of the depletion region Ws created by the surface charges, nearly irrespectively of the epilayer doping or semiconductor type. The more realistic SCCM indicates that, at low frequencies, when the surface charges are able to follow the variations of the applied voltage, the value of beta approaches the one obtained without surface charges,while the high-frequency value (the significant one) is smaller.Spanish MINECO and FEDER under Project TEC2017-83910-R and Junta de Castilla y León and FEDER under Project SA254P18

    “Adquisición de competencias en mecatrónica mediante el aprendizaje basado en mini-proyectos”

    Get PDF
    Memoria ID-298. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2013-2014.[ES] El presente proyecto tenía como principal objetivo abordar, mediante el aprendizaje basado en mini-proyectos, la adquisición de competencias de mecatrónica (disciplina que aúna la Mecánica y la Electrónica) en la asignatura “Electrónica de los sistemas mecánicos”, del cuarto curso del grado en Ingeniería Mecánica impartido en la Escuela Politécnica Superior de Zamora. En el caso de las ingenierías, esta metodología parece particularmente interesante dada la propia naturaleza de la carrera profesional asociada. En el aprendizaje basado en proyectos (ABP), cuyo eje fundamental gira precisamente en torno a la mejora en la adquisición de competencias, los estudiantes asumen un mayor protagonismo en el proceso de aprendizaje, con una mayor autonomía, responsabilidad y grado de libertad a la hora de enfocar las tareas propias de cada materia. El profesor pasa a ser un mentor y guía del proceso, encargado de orientar adecuadamente a los estudiantes, tanto en relación a la 2 identificación de los problemas que surjan en el desarrollo de los proyectos como respecto la búsqueda de fuentes de información necesarias para su consecución. En esta acción de innovación docente, el aprendizaje basado en proyectos ha sido planteado en una escala más reducida y controlada, al ser el primer año en que se impartía la asignatura. Para ello se ha optado por desarrollar, en el último tramo de la asignatura, pequeños proyectos de 3 o 4 semanas de duración, lo que nos ha permitido disponer de flexibilidad para asegurar la impartición de todos los contenidos así como controlar de manera adecuada la evolución del aprendizaje de los alumnos. Estos objetivos se han llevado a cabo de manera satisfactoria gracias a una serie de actuaciones concretas que pasamos a describir a continuación

    Monte Carlo model for the analysis and development of III-V Tunnel-FETs and Impact Ionization-MOSFETs

    Get PDF
    Impact-ionization metal-oxide-semiconductor FETs (I-MOSFETs) are in competition with tunnel FETs (TFETs) in order to achieve the best behaviour for low power logic circuits. Concretely, III-V I-MOSFETs are being explored as promising devices due to the proper reliability, since the impact ionization events happen away from the gate oxide, and the high cutoff frequency, due to high electron mobility. To facilitate the design process from the physical point of view, a Monte Carlo (MC) model which includes both impact ionization and band-to-band tunnel is presented. Two ungated InGaAs and InAlAs/InGaAs 100 nm PIN diodes have been simulated. In both devices, the tunnel processes are more frequent than impact ionizations, so that they are found to be appropriate for TFET structures and not for I-MOSFETs. According to our simulations, other narrow bandgap candidates for the III-V heterostructure, such as InAs or GaSb, and/or PININ structures must be considered for a correct I-MOSFET design

    Time-domain Monte Carlo simulation of GaN planar Gunn nanodiodes in resonant circuits

    Get PDF
    In this work we present a theoretical study based on time-domain Monte Carlo (MC) simulations of GaN-based Self-Switching Diodes (SSDs) oriented to the experimental achievement and control of the sub-THz Gunn-oscillations potentially provided by these devices. With this aim, an analysis of the frequency performance of SSDs connected to a resonant RLC parallel circuit, is reported here. V-shaped SSDs have been found to be more efficient, in terms of the DC to AC conversion efficiency η, than similar square-shape ones. Indeed, a value of η of at least 0.80%, can be achieved with appropriate RLC elements, even when considering heating effects. When the influence of parasitic elements such as the crosstalk capacitance Ctalk is evaluated, MC simulations have shown that the resonant circuit must contain a capacitance C higher than Ctalk in order to obtain experimentally useful values of η. This condition can be reached by integrating a sufficiently high number N of parallel SSDs in the fabricated devices. MC simulations have also shown that when several diodes are fabricated in parallel the oscillations of all the SSDs are not synchronized, but this problem is solved by the attachment of a resonant RLC tank
    corecore