2. Maestría

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Tesis de la Escuela de Posgrado

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search.filters.applied.f.advisor: search.filters.advisor.Guerra Torres, Jorge AndrésSubject: search.filters.subject.https://purl.org/pe-repo/ocde/ford#2.05.01

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    Estudio de la posibilidad de utilizar una cámara CCD chaeleon para obtener imágenes de la fluorescencia de la vegetación a nivel de campo
    (Pontificia Universidad Católica del Perú, 2017-03-10) Loayza Loza, Hildo Mac Lean; Moya Marco, Ismael; Guerra Torres, Jorge Andrés
    La agricultura es una actividad económica esencial para el desarrollo humano y es el sustento de millones de personas fomentando la seguridad alimentaria e impulsando la economía de países en desarrollo. Sin embargo la producción agrícola es afectada por diferentes factores abióticos (cambio climático) y bióticos (plagas y enfermedades) que disminuyen drásticamente su eficiencia. La fotosíntesis es el único mecanismo de entrada de energía de la biosfera y agentes estresantes como, por ejemplo, la escasez de agua limitan la conductancia estomática en las hojas disminuyendo la entrada de CO2 en las plantas lo que conlleva a una reducción de la fotosíntesis (Flexas et al., 2002a; Flexas y Medrano 2002a). Por estos motivos, resulta importante detectar el estrés antes que los síntomas visuales sean evidentes.
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    On the fundamental absorpion of amorphous semiconductors
    (Pontificia Universidad Católica del Perú, 2016-06-20) Angulo Abanto, José Rubén; Guerra Torres, Jorge Andrés
    The present thesis reviews different models that describe the fundamental absorption of amorphous semiconductors. These models make use of the electronic density of states to shape the absorption coefficient in the fundamental absorption region. The study focuses on the optical absorption of hydrogenated amorphous Silicon (a-Si:H), hydrogenated and non-hydrogenated amorphous silicon carbide (a-SiC:Hx), and silicon nitride (a-SiN) thin films. On the one hand, parameters like the Tauc-gap and Urbach energy are obtained from the absorption coefficient using the traditional models. On the other hand, a recently proposed model based on band thermal fluctuations was assessed [1]. This model allows a determination of the mobility gap and the Urbach energy from a single fit of the absorption coefficient without the need of identifying the Tauc region beforehand. Furthermore, it is able to discriminate the variation of the Urbach energy from the bandgap. The results allow the evaluation of the aforementioned parameters with annealing treatments at different temperatures. The mobility edges are insensitive to the structural disorder by at least one degree lower than the Urbach energy. This work demonstrates that it is possible to obtain the mobility edge through this model. In addition, the measured Tauc-gap and Urbach energy exhibit a strong linear correlation following the Cody model for all three materials. Finally, the Urbach focus concept is evaluated and estimated under different analysis.