In this work, a detailed study on the effect of ambient and beam profile in the crystallization of a-Si thin films is presented. A Q switched Nd³⁺: YAG laser, with the wavelength 532 nm and pulse duration 6 ns FWHM is considered. Laser annealing is performed with a Gaussian beam and flat-top beam profile on 400 nm and 1000 nm thick a-Si films deposited on c-Si substrate. In order to induce annealing along with texturing of surface, laser beam overlap technique with a 90% spot overlapping is used. Experiments are perfomed in air and in water ambience. XRD peaks corresponding to poly-silicon thin film are observed with the Nd³⁺:YAG laser treatment. Raman spectroscopy analysis confirms the formation of poly crystalline films. Changes in surface morphology is observed using Scanning Electron Microscope. In theoretical simulation, thermal modeling is used and nanosecond laser induced annealing at a longer wavelength has been found to be suitable for crystallization of thick amorphous silicon films but results in heating the substrate.

Date Published: 12 March 2015
PDF: 10 pages
Proc. SPIE 9351, Laser-based Micro- and Nanoprocessing IX, 93511I (12 March 2015); doi: 10.1117/12.2079750

Published in SPIE Proceedings Vol. 9351:
Laser-based Micro- and Nanoprocessing IX
Udo Klotzbach; Kunihiko Washio; Craig B. Arnold, Editor(s)