Irradiation effect on Ag-dispersed amorphous silicon thin films by femtosecond laser

Anran Guo; Nasir Ilyas; Yuhao Song; Renfang Lei; Hao Zhong; Dongyang Li; Wei Li

doi:10.1117/12.2524107

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29 March 2019 Irradiation effect on Ag-dispersed amorphous silicon thin films by femtosecond laser

Anran Guo, Nasir Ilyas, Yuhao Song, Renfang Lei, Hao Zhong, Dongyang Li, Wei Li

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Proceedings Volume 11046, Fifth International Symposium on Laser Interaction with Matter; 1104629 (2019) https://doi.org/10.1117/12.2524107
Event: Fifth International Symposium on Laser Interaction with Matter, 2018, Changsha, China

Abstract

The structural and optical properties of amorphous silicon (a-Si) and Ag-dispersed amorphous silicon (a-Si:Ag) thin films irradiated by femtosecond (fs) laser at various energy densities are investigated comparatively in this article. It is found that at a lower energy density of 100 mg/cm² , the film microstructure evolves from a completely amorphous phase to an intermediate one containing both amorphous and polycrystalline silicon. During laser irradiation, the formation of nanocrystals in a-Si films begins at lower energy density, but the existing Ag nanoparticles inhibits somehow the crystallization of a-Si in a-Si:Ag films at the same energy density. As the energy density is increased to a moderate value of 200 mj/cm² , the surface of a-Si:Ag films featuring a vertically aligned pillar-shaped structure is emerging. Both the crystallinity and the root mean square of surface roughness exhibit a monotonic increase with the increase of energy density. The Ag nanoparticles are dispersed uniformly in a silicon matrix, resulting in a resonant light absorption due to so-called localized surface plasmon. The localized surface plasmon resonance (LSPR) wavelengthes of the irradiated aSi:Ag films are increased significantly from 600 nm to about 820 nm, and the bandwidth of the measured absorptance is enhanced in the range of 600~1600 nm. The nanocrystallization mechanism, the formation of pillar-shaped structures and the light absorption enhancement are explained regarding the high electron density and the plasma-surface interactions.

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Anran Guo, Nasir Ilyas, Yuhao Song, Renfang Lei, Hao Zhong, Dongyang Li, and Wei Li "Irradiation effect on Ag-dispersed amorphous silicon thin films by femtosecond laser", Proc. SPIE 11046, Fifth International Symposium on Laser Interaction with Matter, 1104629 (29 March 2019); https://doi.org/10.1117/12.2524107

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