A SiGe Slot Approach for Enhancing Strain Induced Pockels Effect in the Mid-IR Range

[EN] Strained silicon was proposed more than a decade ago promising to revolutionize the silicon photonics field by allowing efficient modulation in this platform. Despite all the efforts, still rather low chi(2) values have been measured in strained silicon devices. In addition, the way of applying strain has not barely changed since the concept was proposed, usually consisting on a silicon waveguide covered by a stressor material such as silicon nitride. In this letter, a SiGe slot approach is explored as a different route to enhance the strain induced Pockels effect in the mid-IR range. Such approach would allow effective index change values which are near to 10(-4) and improve the values expected for the most common silicon - silicon nitride structure by more than three orders of magnitude.This work was supported in part by the Ministerio de Ciencia e Innovacion under Grant TEC2016-76849 and Grant PID2019-111460GB-I00 and in part by the Generalitat Valenciana under Grant PROMETEO/2019/123.Olivares-Sánchez-Mellado, I.; Sanchis Kilders, P. (2021). A SiGe Slot Approach for Enhancing Strain Induced Pockels Effect in the Mid-IR Range. IEEE Photonics Technology Letters. 33(16):848-851. https://doi.org/10.1109/LPT.2021.3075753848851331

Enhanced Pockels effect in strained silicon by means of a SiGe/Si/SiGe slot structure

[EN] A slot waveguide structure made of a SiGe/Si/SiGe heterojunction is proposed to enhance Pockels effect in strained silicon. The strain is applied via lattice mismatch between layers, while the slot configuration optimizes the overlap between the optical and electric field inside the strained silicon.Funding from projects TEC2016-76849 (MINECO/FEDER, UE) and PROMETEO/2019/123 (Generalitat Valenciana) is acknowledged. Irene Olivares acknowledges the UPV for funding her research staff training (FPI) grant.Olivares-Sánchez-Mellado, I.; Sanchis Kilders, P. (2020). Enhanced Pockels effect in strained silicon by means of a SiGe/Si/SiGe slot structure. IEEE. 1-2. https://doi.org/10.1109/IPC47351.2020.9252351S1

Tactile Sensing with Accelerometers in Prehensile Grippers for Robots

This is the author’s version of a work that was accepted for publication in Mechatronics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Mechatronics, Vol. 33, (2016)] DOI 10.1016/j.mechatronics.2015.11.007.Several pneumatic grippers with accelerometers attached to their fingers have been developed and tested. The first gripper is able to classify the hardness of different cylinders, estimate the pneumatic pressure, monitor the position and speed of the gripper fingers, and study the phases of the action of grasping and the influence of the relative position between the gripper and the cylinders. The other grippers manipulate and assess the firmness of eggplants and mangoes. To achieve a gentle manipulation, the grippers employ fingers with several degrees of freedom in different configurations and have a membrane filled with a fluid that allows their hardness to be controlled by means of the jamming transition of the granular fluid inside it. To assess the firmness of eggplants and mangoes and avoid the influence of the relative position between product and gripper, the firmness is estimated while the products are being held by the fingers. Better performance of the accelerometers is achieved when the finger employs the granular fluid. The article presents methods for designing grippers capable of assessing the firmness of irregular products with accelerometers. At the same time, it also studies the possibilities that accelerometers, attached to different pneumatic robot gripper fingers, offer as tactile sensors. (C) 2015 Elsevier Ltd. All rights reserved.This research is supported by the MANI-DACSA project (Grant number RTA2012-00062-C04-02), which is partially funded by the Spanish Government (Ministerio de Economia y Competitividad.).Blanes Campos, C.; Mellado Arteche, M.; Beltrán Beltrán, P. (2016). Tactile Sensing with Accelerometers in Prehensile Grippers for Robots. Mechatronics. 33:1-12. https://doi.org/10.1016/j.mechatronics.2015.11.007S1123

Cursos masivos abiertos en línea (MOOC), habilidades blandas y rendimiento académico en los estudiantes del posgrado en Administración de la Universidad Nacional de San Antonio Abad del Cusco - 2019

El objetivo de este estudio es analizar la causalidad que tiene el uso de los MOOC y habilidades blandas sobre el rendimiento académico de los estudiantes de Posgrado de la UNSAAC en el año 2019. La investigación es no experimental explicativa, de corte transversal. La unidad de análisis corresponde a los estudiantes matriculados en el año 2019 en la escuela de Posgrado – Unidad Administración, se estableció una población de 312 profesionales, al utilizar la técnica de muestreo probabilístico simple se obtuvo información de 192 encuestados. Para la recolección de datos se utilizó un cuestionario confiable y validado conformado por 100 reactivos, aplicado al grupo muestral durante 60 días, este cuestionario tiene la característica de medir a través de una escala de profundidad del tipo Likert las variables. Para probar la hipótesis se aplicó en un primer nivel de análisis la estadística descriptiva y en segundo nivel un análisis de regresión lineal múltiple y análisis de escalamiento multidimensional. Los principales resultados muestran que existe relación entre los MOOCS y habilidades blandas frente al rendimiento académico; asimismo, se presenta una propuesta de modelo teórico desarrollado a partir de la base teórica y los resultados obtenidos a partir de la estadística

Non-Volatile Photonic Memory Based on a SAHAS Configuration

[EN] The non-volatile memory is a crucial functionality for a wide range of applications in photonic integrated circuits, however, it still poses a challenge in silicon photonic technology. This problem has been overcome in the microelectronic industry by using SONOS (silicon-oxide-nitride-oxide-silicon) memory cells, in which the non-volatility is enabled by a dielectric trapping layer such as silicon nitride. Analogously, in this work, a similar approach in which the nitride has been replaced by a hafnium oxide layer, named as SAHAS configuration, is proposed for enabling a programmable erasable photonic memory fully compatible with the silicon platform. The structure features an efficient performance with writing and erasing times of 100 mu s, retention times over 10 years and energy consumption in the pJ range, which improve the current SONOS or floating gate based photonic approaches that exploit the plasma dispersion effect in silicon. The proposed non-volatile photonic memory device shows an extinction ratio above 12 dB and insertion losses below 1 dB in a compact footprint. In addition, because the memory is optically read, ultrafast access times in the picosecond range are also achieved.This work was supported in part by Ministerio de Economia y Competitividad (MINECO/FEDER, UE) (TEC2016-76849), in part by Generalitat Valenciana (PROMETEO/2019/123), in part by Ministerio de Ciencia e Innovacion (MINECO/FEDER, UE) (PID2019-111460GB-I00, FPU17/04224), and in part by Universitat Politecnica de Valencia (FPI Grant).Olivares-Sánchez-Mellado, I.; Parra Gómez, J.; Sanchis Kilders, P. (2021). Non-Volatile Photonic Memory Based on a SAHAS Configuration. IEEE Photonics Journal. 13(2):1-9. https://doi.org/10.1109/JPHOT.2021.3060144S1913

On the influence of interface charging dynamics and stressing conditions in strained silicon devices

[EN] The performance of strained silicon devices based on the deposition of a top silicon nitride layer with high stress have been thoroughly analyzed by means of simulations and experimental results. Results clearly indicate that the electro-optic static response is basically governed by carrier efects. A frst evidence is the appearance of a variable optical absorption with the applied voltage that should not occur in case of having a purely electro-optic Pockels efect. However, hysteresis and saturation efects are also observed. We demonstrate that such efects are mainly due to the carrier trapping dynamics at the interface between the silicon and the silicon nitride and their infuence on the silicon nitride charge. This theory is further confrmed by analyzing identical devices but with the silicon nitride cladding layer optimized to have intrinsic stresses of opposite sign and magnitude. The latter is achieved by a post annealing process which produces a defect healing and consequently a reduction of the silicon nitride charge. Raman measurements are also carried out to confrm the obtained results.Funding from projects TEC2016-76849-C2-2-R (MINECO/FEDER, UE) and NANOMET PLUS-Conselleria d'EducaciA3, Cultura i Esport - PROMETEOII/2014/034 is acknowledged. Irene Olivares also acknowledges the Universitat Politecnica de Valencia for funding his research staff training (FPI) grant. The authors would also like to thank Steven Van Roye from Ghent University for participating in the measurements of the annealed samples.Olivares-Sánchez-Mellado, I.; Ivanova-Angelova, T.; Sanchis Kilders, P. (2017). On the influence of interface charging dynamics and stressing conditions in strained silicon devices. Scientific Reports. 7(7241):1-8. https://doi.org/10.1038/s41598-017-05067-91877241Reed, G. T., Mashanovich, G., Gardes, F. Y. & Thomson, D. J. Silicon optical modulators. 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Phase-matched sum frequency generation in strained silicon waveguides using their second-order nonlinear optical susceptibility. Optics Express 19, 21707–21716 (2011).Schriever, C., Bohley, C., Schilling, J. & Wehrspohn, R. B. Strained Silicon Photonics. Materials 5, 889–908 (2012).Bianco, F. et al. Two-dimensional micro-Raman mapping of stress and strain distributions in strained silicon waveguides. Semiconductor Science and Technology 27, 085009 (2012).Chmielak, B. et al. Investigation of local strain distribution and linear electro-optic effect in strained silicon waveguides. Optics Express 21, 25324–25332 (2013).Aleali, A., Xu, D., Schmid, J. H., Cheben, P. & Winnie, N. Y. Optimization of stress-induced pockels effect in silicon waveguides for optical modulators. In Group IV Photonics (GFP), 2013 IEEE 10th International Conference on, 109–110 (IEEE, 2013).Puckett, M. W., Smalley, J. S., Abashin, M., Grieco, A. & Fainman, Y. Tensor of the second-order nonlinear susceptibility in asymmetrically strained silicon waveguides: analysis and experimental validation. Optics Letters 39, 1693–1696 (2014).Damas, P. et al. Wavelength dependence of pockels effect in strained silicon waveguides. Optics Express 22, 22095–22100 (2014).Khurgin, J. B., Stievater, T. H., Pruessner, M. W. & Rabinovich, W. S. On the origin of the second-order nonlinearity in strained Si-SiN structures. JOSA B 32, 2494–2499 (2015).Manganelli, C. L., Pintus, P. & Bonati, C. Modeling of strain-induced Pockels effect in Silicon. Optics Express 23, 28649–28666 (2015).Damas, P., Marris-Morini, D., Cassan, E. & Vivien, L. Bond orbital description of the strain-induced second-order optical susceptibility in silicon. Physical Review B 93, 165208 (2016).Cazzanelli, M. et al. Second-harmonic generation in silicon waveguides strained by silicon nitride. Nature Materials 11, 148–154 (2012).Schriever, C. et al. Second-Order Optical Nonlinearity in Silicon Waveguides: Inhomogeneous Stress and Interfaces. Advanced Optical Materials 3, 129–136 (2015).Borghi, M. B. et al. High-frequency electro-optic measurement of strained silicon racetrack resonators. Optics Letters 40, 5287–5290 (2015).Azadeh, S. S., Merget, F., Nezhad, M. & Witzens, J. On the measurement of the Pockels effect in strained silicon. Optics Letters 40, 1877–1880 (2015).Sharma, R. et al. Effect of dielectric claddings on the electro-optic behavior of silicon waveguides. Optics Letters 41, 1185–1188 (2016).Borghi, M. et al. Homodyne Detection of Free Carrier Induced Electro-Optic Modulation in Strained Silicon Resonators. Journal of Lightwave Technology 34, 5657–5668 (2016).Olivares, I., Ivanova, T., Pinilla-Cienfuegos, E. & Sanchis, P. A systematic optimization of design parameters in strained silicon waveguides to further enhance the linear electro-optic effect. In SPIE Photonics Europe, 98910E-98910E (International Society for Optics and Photonics, 2016).Warren, W. L., Lenahan, P. & Curry, S. E. First observation of paramagnetic nitrogen dangling-bond centers in silicon nitride. Physical review letters 65, 207 (1990).Warren, W., Kanicki, J., Robertson, J., Poindexter, E. & McWhorter, P. Electron paramagnetic resonance investigation of charge trapping centers in amorphous silicon nitride films. Journal of applied physics 74, 4034–4046 (1993).Bazilchuk, M., Haug, H. & Marstein, E. S. Modulating the fixed charge density in silicon nitride films while monitoring the surface recombination velocity by photoluminescence imaging. Applied Physics Letters 106, 143505 (2015).Stathis, J. H. & Zafar, S. The negative bias temperature instability in MOS devices: A review. Microelectronics Reliability 46, 270–286 (2006).Alam, M. A. & Mahapatra, S. A comprehensive model of PMOS NBTI degradation. Microelectronics Reliability 45, 71–81 (2005).Kufluoglu, H. & Alam, M. A. A computational model of NBTI and hot carrier injection time-exponents for MOSFET reliability. Journal of Computational Electronics 3, 165–169 (2004).Schmidt, J., Schuurmans, F. M., Sinke, W. C., Glunz, S. W. & Aberle, A. G. Observation of multiple defect states at silicon-silicon nitride interfaces fabricated by low-frequency plasma-enhanced chemical vapor deposition. Applied Physics Letters 71, 252–254 (1997).Sanjoh, A., Ikeda, N., Komaki, K. & Shintani, A. Analysis of Interface States between Plasma-CVD Silicon Nitride and Silicon-Substrate Using Deep-Level Transient Spectroscopy. Journal of The Electrochemical Society 137, 2974–2979 (1990).Martnez, F., Mártil, I., González-Daz, G., Selle, B. & Sieber, I. Influence of rapid thermal annealing processes on the properties of SiN x :H films deposited by the electron cyclotron resonance method. Journal of non-crystalline solids 227, 523–527 (1998).Martnez, F. et al. Thermal stability of a-SiN x :H films deposited by plasma electron cyclotron resonance. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 17, 1280–1284 (1999)

Heterogeneidade no envolvimento do bullying escolar: Uma análise das classes latentes

The present study aimed to develop a typology of school bullying through a statistical technique that minimizes the classification error in groups. This typology allows examining how multiple attributes of bullying coexist in people without artificially separating those attributes. Using a latent class analysis, six items that represented the role of the witness, the victim, and the aggressor were modeled in school bullying situations in a sample of 440 Chilean schoolchildren between 14 and 20 years of age (M = 16,30 and SD = 1,42). Two models are reported with four and five latent classes, respectively. In the four-class model, it can be seen a group called “Not Involved” (14,5%) which has not been implicated in any of the roles of harassment; another group called “Witness” (56,2%) which has only been involved as a witness in bullying situations; a group called “Witness and Victim” (13,3%) which has been involved as a witness and victim in school bullying situations; and finally, a group called “Witness, Victim and Aggressor” (16%) which has been involved in all roles. In the five-class model, the same groups are observed, plus one denominated as “Witness and Aggressor” implicated as a witness and aggressor in school bullying situations. The results show that most of the student body has been involved in bullying situations and that an important part has been involved in more than one role, which implies that victimization and perpetration of bullying are not mutually exclusive.El presente estudio tuvo como objetivo desarrollar una tipología de acoso escolar a través de una técnica estadística que minimiza el error de clasificación en los grupos. Esta tipología permite examinar cómo múltiples atributos del acoso escolar coexisten en las personas, sin separarlos artificialmente. Utilizando un análisis de clases latentes se modelaron seis ítems que representaban los roles de testigo, víctima y sujeto agresor en situaciones de acoso en 440 escolares de Chile, cuya edad fluctuó entre 14 y 20 años (M = 16,30 y DE = 1,42). Se reportan dos modelos con cuatro y cinco clases respectivamente. En el primer modelo se observa un grupo denominado como “No involucrado” (14,5%) el cual no ha participado en situaciones de acoso; un grupo denominado como “Testigo” (56,2%) el cual solamente se ha involucrado como testigo en dichas situaciones; un grupo denominado como “Testigo y víctima” (13,3%) el cual se ha implicado como testigo y víctima en situaciones de acoso y, finalmente, un grupo denominado como “Testigo, víctima y agresor” (16%) el cual se ha implicado en todos los roles. En el modelo de cinco clases se observan los mismos grupos, más uno denominado como “Testigo y agresor” que se ha implicado como testigo y agresor en acoso escolar. Los resultados indican que la mayoría del estudiantado se ha involucrado en situaciones de acoso y que una parte importante se ha involucrado en más de un rol, lo que implica que la victimización y la perpetración del acoso no son mutuamente exclusivos.O presente estudo teve como objetivo desenvolver uma tipologia de bullying através de uma técnica estatística que minimiza o erro de classificação nos grupos. Essa tipologia nos permite examinar como os múltiplos atributos do bullying coexistem nas pessoas sem separá-los artificialmente. Usando uma análise de classe latente, seis itens foram modelados representando os papéis de testemunha, vítima e sujeito agressor em situações de bullying em 440 estudantes chilenos entre 14 e 20 anos de idade (M = 16,30 e DE = 1,42). Dois modelos com quatro e cinco classes latentes são relatados respectivamente. No modelo de quatro classes há um grupo chamado “Não envolvido” (14,5%), que não esteve envolvido na participação de bullying, um grupo chamado “Testemunha” (56,2%), que só esteve envolvido como testemunha em situações de bullying, um grupo chamado “Testemunha e vítima” (13,3%) que esteve envolvido como testemunha e vítima em situações de assédio e finalmente um grupo chamado “Testemunha, vítima e agressor” que esteve envolvido em todas as funções. No modelo de cinco classes, os mesmos grupos são observados, e mais um chamado “Testemunha e agressor” (16%), que esteve envolvido como testemunha e agressor no bullying. Os resultados indicam que a maioria dos estudantes já se envolveu em situações de bullying e que uma parte importante esteve envolvida em mais de uma função, o que implica que a vitimização e a perpetração de bullying não são mutuamente exclusivos

Confiabilidad y validez de la Escala de Déficit Atencional (EDAH) adaptada en estudiantes chilenos

Antecedentes. Las necesidades de atención en salud mental infantil hacen necesario contar con estudios epidemiológicos que sirvan de base para perfeccionar las intervenciones y acrecentar el diagnóstico, con instrumentos fiables y adecuados al contexto. Objetivo. El objetivo de este estudio fue analizar las propiedades psicométricas de la Escala para la Evaluación del Trastorno por Déficit Atencional (EDAH), en escolares de primaria y secundaria de Chile. Método. Se evaluó una muestra de 508 alumnos (144 con Déficit Atencional, 110 con sospecha de padecerlo y 254 comunes) mediante un test completado por sus profesores. Resultados. La estructura factorial de la EDAH reveló tres factores que en conjunto explican el 71,61% de la varianza total de la escala, con un coeficiente Alfa de 0,948. Esto permite concluir que la adaptación de la escala presenta características psicométricas aceptables, una adecuada consistencia interna y que sus elementos poseen un adecuado poder discriminatorio. Discusión y conclusión. Se efectuó el estudio transversal de salud mental en escolares chilenos, el cual reveló que la escala EDAH adaptada posee alta capacidad de discriminación, adecuada fiabilidad de elementos y factores, además de presentar un óptimo poder discriminante entre factores. Se analizan las implicaciones y el posible aporte en la detección precoz del diagnóstico clínico en salud mental.Background. The needs of children’s mental health care make it necessary to have epidemiological studies that serve as a basis to refine the interventions and enhance the diagnosis with reliable and appropriate tools. Objective. The objective of this study was to analyze the psychometric properties of the scale for the assessment of the Attentional Deficit Disorder (ADHD) in primary and secondary schools in Chile. Method. A sample of 508 students (144 with Attentional deficits, 110 with suspected autism and 254 common) was assessed through a test completed by their teachers. Results. The factorial structure of the ADHD revealed that three factors explain together the 71.61 % of the total variance of the scale, with a coefficient alpha of 0,948. This allows us to conclude that the scale presents acceptable psychometric characteristics and adequate internal consistency, and that its elements have a suitable discriminatory power. Discussion and conclusion. The present study of mental health in Chilean schoolchildren revealed that the ADHD adapted scale possesses a high discriminant capacity and adequate elements and factors reliability, as well as an optimal discriminant power among factors. We analyze the implications and possible contribution to the early detection of clinical diagnosis in mental health

Caracterización de fuentes de dióxido de azufre en Bahía Banca

Una adecuada gestión del medio ambiente que permita definir una estrategia de mitigación y control de los contaminantes, requiere tanto de metodologías capaces de caracterizar la calidad del aire, como de reconocer las principales fuentes de emisión de contaminantes y sus contribuciones. En este trabajo se implementa el modelo NTA (Nonparametric Trajectory Analysis), para estimar la distribución de fuentes de emisión y la concentración promedio del SO2 en la ciudad de Bahía Blanca (Provincia de Buenos Aires, Argentina). La herramienta es considerada un modelo receptor híbrido, dado que utiliza mediciones tomadas en el centro de monitoreo y datos meteorológicos locales. Esta metodología, aplicada para distintos periodos temporales, evidencio altas concentraciones al noroeste de la estación de monitoreo, en mayor medida para los meses fríos del año. Si bien Petrobras Argentina S.A. representa solo el 17.2% anual de las emisiones de SO2, es destacable la relevancia de los vientos predominantes en la dispersión de los contaminantes, y consecuente en las áreas de impacto. Como fortaleza de la herramienta, se destaca la posibilidad de proyectar las zonas de mayor amenaza en función de la meteorología, de modo de optimizar los recursos disponibles aplicados a campañas de monitoreo, acotando región potencial de emisión