viernes, 17 de julio de 2009

Posted at the BLOG of SUNY-Albany (II)

Since the first moment that I saw the College of Nanoscale Science and Engineering, I thought that I was in another dimension. While the staff was showing us around the beautiful complex, I became even more excited of my acceptance as a summer intern to CNSE. In my life, I have never seen so much advanced technology in one place. CNSE is the ideal place to do any type of research on nanotechnology.
When I learned about my project, I had no idea what it was, then I met the people I would be working with and they explained the general idea of my project. I still needed to learn more details about my project, so I had to read about thirty papers to understand. That was my first task: just reading. When I finished reading, I did not understand much; however, every day I learn something new about my project.
The name of my project is "Modeling resist performance". The problem here is that when we want to measure the dimensions of the photoresist patterns with the Scanning Electron Microscope (SEM), there is a reaction between the resist and the electrons. Consequentially, the resist suffers a change called "shrinkage phenomenon". In other words, the photoresist shrinks and the dimensions change too. If we scan more with the SEM, the photoresist shrinks more. So, how do we get the true measurements? By using an Atomic Force Microscope (AFM) we can get the true measurements without damaging the resist. But this tool is not used to do that, because it is slower than a SEM. The best way to understand the phenomenon is just modeling it with math. So, I am working with MatLab program and comparing with the real data from AFM.

Daniel Bellido Aguilar, CNSE Intern

June 23, 2009

Posted at the BLOG of SUNY-Albany

Since the beginning of my internship at CNSE, I have learned many things: from simpler ideas such as the safety requirements to work in the lab, to more complex skills like preparing different kind of compounds. Being here made me realize that you need to be very careful in every action you do; everything is important and a little change can alter your product.
The project I'm working on for my internship is synthesizing acid amplifiers. These compounds are part of a photoresist. The resist is a polymer that covers the silicon wafer. The resist film can be imaged using EUV light. The goal of the project is to improve the resist resolution, LER (Line Edge Roughness), and sensitivity so that smaller computer chips can be made. The photoresist prepared with acid amplifiers works with EUV lithography. The EUV light has a wavelength of approximately 13.5nm. When it comes over the wafer, it interacts with another part of the photoresist called PAG (Photo Acid Generator), to generate an acid which interacts with the acid amplifier to generate more acid in an autocatalytic way.
My participation during my internship consists of preparing some acid amplifiers. I am also working with software to simulate the strength of the bonds in the compounds and learning a little bit about how to get NMR spectrums.

Sara Cruz, CNSE Intern

July 6, 2009

lunes, 13 de julio de 2009

Síntesis de nanorodillos de ZnO por el método hidrotermal

Hola aquí les pongo mi resumen de la estancia de investigación en ensenada

Roberto González Rodríguez1, Manuel Herrera Zaldívar2
Universidad de las Américas Puebla, Cholula Puebla
Centro de Nanociencias y Nanotecnología-UNAM Ensenada, BC

El ZnO posee propiedades catalíticas, semiconductoras, optoelectrónicas y piezoeléctricas que le convierten en uno de los materiales más prometedores para la fabricación de dispositivos emisores de luz, transistores, láseres UV, sensores químicos, guías de onda, y celdas solares1. Dado que la síntesis de nanoestructuras de este semiconductor posibilita el incrementar su brecha de energía prohibida y su eficiencia cuántica,2 existe un enorme interés por mejorar los método de crecimiento actuales. Entre los métodos químicos para la síntesis de nanoestructuras de ZnO se encuentra el método hidrotermal, que ofrece las ventajas de ser económico, operar a baja temperatura (100 C) y permitir sintetizar una gran variedad de nanoestructuras impurificadas con otros elementos.3,4 Las desventajas de este método radican principalmente en la incorporación indeseada de impurezas y en la inhomogeneidad de la morfología de las nanoestructuras obtenidas.

En este trabajo se hace un estudio sobre el efecto del pH, del tipo de surfactante usado y la concentración de este en la síntesis hidrotermal de nanorodillos de ZnO. Las muestras obtenidas fueron caracterizadas por microscopía electrónica de barrido (SEM), espectroscopía de energía dispersa (EDS) y Catodoluminscencia (CL). Se demuestra que el efecto del surfactante impacta de manera significativa en la morfología de los nanorodillos, ya que a bajas concentraciones se obtiene una morfología irregular de los cristalitos de ZnO, mientras que el surfactante a altas concentraciones impide la nucleación del ZnO. Hemos demostrado además que el pH modifica ligeramente la morfología de los nanorodillos. A pH = 13 se obtuvieron estructuras con forma de agujas de 3-4 micras de longitud, y a pH = 14 se obtuvieron nanorodillos con forma de conos truncados. Nuestro estudio de CL reveló que los nanorodillos presentan una emisión de borde de banda centrada en 390 nm y una intensa emisión de defectos centrada en 600 nm. Los nanorodillos sintetizados con 12 ml de surfactante (etilen diamina) y pH = 13 presentan una mayor intensidad relativa de la emisión de borde de banda, lo que indica que poseen mayor calidad cristalina que los sintetizados con diferentes concentraciones de surfactante. Este resultado se soporta en la homogeneidad morfológica de los nanorodillos observada por SEM.

Proyecto PAPIME PE100409, PAPIIT-UNAM (IN107208).

[1] Joydepp Dutta, Sunandan Baruah, “Hydrothermal growth of ZnO nanostructures”, Science and Technology of Advanced Materials 10 (2009) 013001
[2] Yu C. Chang and Lih j. Chen. “ZnO nanoneedles with enhanced and sharp ultraviolet cathodoluminescence peak”, J Phys. Chem. C 2007, 111, 1268-1272.
[3] Young Mu Oh, Kyung Moon Lee, Kyung Ho Park, “Correlating Luminescence from individual ZnO Nanostructures with electronic Transport Characteristics”, Nanoletters 2007, Vol 7, No. 12 3681-3685.
[4] L. N. Dem’yanets, T. G. Uvarova, “Zinc Oxide: Hydrothermal growth of nano and bulk crystals and their luminescent properties”, J. Mater Sc. 41 (2006) 1439-1444

jueves, 2 de julio de 2009

Nanopartículas de ZnO fluorescentes

Estas fotos son resultado de Lizzet Montiel Calzada, estudiante de la UAT trabajando este verano en nuestros laboratorios.

¡ Muy bonitas nanopartículas fluorescentes de óxido de Zinc !