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Please use this identifier to cite or link to this item: http://hdl.handle.net/10119/3992

Title: Surface modification of an amorphous Si thin film crystallized by a linearly polarized Nd:YAG pulse laser beam
Authors: Horita, Susumu
Kaki, Hirokazu
Nishioka, Kensuke
Issue Date: 2007-07
Magazine name: Journal of Applied Physics
Volume: 102
Number: 1
Start page: 103501-1
End page: 103501-10
DOI: 10.1063/1.2751085
Abstract: Amorphous Si films of 60 and 10 nm thick on glass substrates were irradiated by a linearly polarized Nd:YAG pulse laser with the wavelength λ=532 nm at the incident angle θ_i=0. The surface of the irradiated 60-nm-thick film had both periodic ridges perpendicular to the electric field vector E and aperiodic ridges roughly parallel to E, where the spatial period of the periodic ridges was almost λ.From the continuous 10-nm-thick film, the separate rectangular Si islands were formed with a periodic distance of λ, with the edges parallel or perpendicular to E. When θ_i was increased from normal incidence of the s-polarized beam for a 60-nm-thick film, the aperiodic ridges were reduced while the periodic ridges were still formed. For a 10-nm-thick film, the Si stripes were formed perpendicular to E, using the s-polarized beam at θ_i=12°. In order to investigate the mechanisms of the surface modifications of, in particular, aperiodic ridges, islands, and stripes, we improved the previous theoretical model of the periodic distribution of the beam energy density (periodic E-D) generated by irradiation of the linearly polarized laser beam, taking account of the multireflection effect in the Si film which is semitransparent for λ. Further, the calculated E-D was corrected with respect to the thermal diffusion in the irradiated Si film. The calculation results show that the two-dimensional E-D consists of a constant or a dc term and a sinusoidal or an ac term which contains various spatial periods. The multireflection effect strongly influences the amplitude and phase of every ac term, which means that the amplitude and phase depend on the film thickness. The thermal diffusion during the heating of the irradiated film greatly reduces the amplitudes of the acterms with periods below the thermal diffusion length. The theoretical calculation showed that, by increasing θ_i, the temperature distribution in the irradiated Si film was changed from two-dimensional toward one-dimensional, which can explain the above experimental results reasonably.
Rights: Copyright 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in S. Horita, H. Kaki, and K. Nishioka, Journal of Applied Physics 102(1), 013501 (2007) and may be found at http://link.aip.org/link/?jap/102/013501.
Type: Article
URI: http://hdl.handle.net/10119/3992
Material Type: publisher
Appears in Collections:c10-1. 雑誌掲載論文 (Journal Articles)

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