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Abstract
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| Laser assisted crystallization and annealing, as a process to produce polycrystalline thin films from amorphous-silicon (a-Si), has been the preferred method for polycrystalline thin-film formation for a number of relevant applications in microelectronics including thin film transistor fabrication. Additionally this topic has emerged again, hand in hand with the impressive growth of laser market in photovoltaic, as a potential solution for polysilicon formation in photovoltaic applications, due of course to the well known effect that grain size has been shown to have on the efficiency of polycrystalline cells. In this particular application, the wide range of different conditions (laser source type, wavelength, pulse width) in which good results in laser annealing of amorphous silicon has been proved, open the door of additional fundamental research of this topic, specially if this research is focused on developing useful information ready to be implemented in production plants. In this sense, laser pulsed annealing using DPSS lasers in the ns range is ideally suited for this purpose bearing in mind the intrinsic advantages that these lasers present for industrial production if compared with other alternatives as excimer or ultrafast lasers sources. In this work we present a detailed study of the wavelength influence in pulsed laser annealing of amorphous silicon thin films, comparing the results for material modification at different fluence regimes in the three fundamental harmonics of standard DPSS laser sources, UV (355 nm), visible (532 nm) and IR (1064 nm). For this study we have irradiated samples of amorphous silicon on glass (deposited by PCVD) and characterized them with MicroRaman techniques for assessing the structural changes induced in the material and the spatial distribution of the different material phases. In order to understand completely the physical mechanisms involved in the process of pulsed laser annealing in the ns regime, a finite element numerical model (FEM) has been developed in COMSOL to simulate the process, and results of the numerical model are presented together with the experimental results, proving that the process can be easily predicted, with an essentially physical model based on heat transport, at different wavelengths and fluence regimes. | |
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International
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Si |
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Congress
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E-MRS Spring 2012 Symposium V. Laser materials processing for micro and nano applications. |
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960 |
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Place
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Estrasburgo (Francia) |
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Reviewers
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Si |
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ISBN/ISSN
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CDP08UPM |
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Start Date
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14/05/2012 |
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End Date
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18/05/2012 |
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From page
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1 |
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To page
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1 |
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E-MRS Spring 2012 Full Program Symposium V. Laser materials processing for micro and nano applications. Publicación electrónica en la web del congreso http://www.emrs-strasbourg.com/ |