Comparison between polysilicon thin films obtained by CW and pulsed laser sources

摘要

Polysilicon thin films on glass substrates have been obtained by Laser Induced Crystallization utilizing two different lasers: a Q-switched diode pumped, frequency-doubled Nd:YLF laser at 523 nm wavelength and a CW Ar{sup}+ laser at 514.5 nm wavelength. Low Pressure Chemical Vapor Deposition (LPCVD) technique has been utilized to prepare intrinsic amorphous films of different thickness. Irradiation parameters of both lasers have been varied in order to study their influence on crystallized material properties. SEM analysis has been applied to determine the grain size and their distribution. Microstructural information is obtained by XRD technique. Optical properties of as-deposited and crystallized films have been determined. Crystallization process by pulsed laser produces materials with grain size larger than that obtained by CW laser, and the best result has been obtained on materials having thickness of 50 nm.