Interferometric femtosecond laser processing for nanostructuring inside thin film

Hydrogenated amorphous silicon (a-Si:H) thin films have been considered for use in solar cell applications because of their significantly reduced cost, however, the overall efficiency and stability are less than that of their bulk crystalline counterparts. Limited work has been performed on solving the efficiency and stability issues of a-Si:H simultaneously. In this study, both surface texturing and crystallization on a-Si:H thin film are achieved through one-step femtosecond laser processing in water. Light absorption is enhanced by light trapping based on surface geometry changes, and the formation of a mixture of hydrogenated microcrystalline silicon (μc-Si:H) and a-Si:H after crystallization suggests that the overall stability may be increased. Furthermore, the formation mechanism for the surface spikes is discussed. A comparison of absorptance spectra for various surface morphologies and crystallinities shows that the combination of surface texturing and crystallization induced by femtosecond laser processing is very promising for a-Si:H thin film solar cell applications.

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Generation of complicated or duplicated structure by interfering femtosecond laser processing of metallic thin film

10.1117/12.874407 ◽

2011 ◽

Author(s):

T. Hiromoto ◽

K. Momoo ◽

Y. Nakata ◽

N. Miyanaga

Keyword(s):

Thin Film ◽

Femtosecond Laser ◽

Laser Processing ◽

Femtosecond Laser Processing ◽

Metallic Thin Film

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Study on femtosecond laser processing with photo excitation for a thin film coated transparent target

The Proceedings of Conference of Kyushu Branch ◽

10.1299/jsmekyushu.2019.72.c41 ◽

2019 ◽

Vol 2019.72 (0) ◽

pp. C41

Author(s):

Yuki HIROTSU ◽

Terutake HAYASHI ◽

Syuhei KUROKAWA ◽

Ryosuke MIZUMACHI

Keyword(s):

Thin Film ◽

Femtosecond Laser ◽

Laser Processing ◽

Femtosecond Laser Processing

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Generation of New Nanomaterials by Interfering Femtosecond Laser Processing

MRS Proceedings ◽

10.1557/proc-850-mm1.4 ◽

2004 ◽

Vol 850 ◽

Cited By ~ 1

Author(s):

Yoshiki Nakata ◽

Okada Tatsuo

Keyword(s):

Thin Film ◽

Femtosecond Laser ◽

Laser Fluence ◽

Laser Processing ◽

The Other ◽

Laser Beams ◽

Nanohole Array ◽

Silica Substrate ◽

Femtosecond Laser Processing ◽

Layered Thin Film

ABSTRACTNew nanomaterials such as nanobump array, nanomesh, nanobelt were generated from thin film processed by interfering femtosecond laser beams. Metallic single- or multi-layered film deposited on a silica substrate was used as a raw thin film. With four interfering femtosecond laser beams, a conical nanobump arrayed in a matrix was generated with single laser shot. As the femtosecond laser fluence increased, the nanobump increased in diameter and height, and a bead was found at the top. Moreover, with three or two interfering femtosecond laser beams, ellipsoidal or linear nanobump array was generated. As an application of a conical nanobump array, field emission from the nanobump array was demonstrated, and the I-V characteristics were measured. On the other hand, with much higher fluence and four interfering femtosecond laser beams, a nanohole array was generated. A nanomesh was also generated from the nanohole array by exfoliating the film. A grating was generated with two interfering femtosecond laser beams, and nanobelts were generated from the grating by exfoliating. Bimetallic nanobelt was also generated from multi-layered thin film.

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Femtosecond Laser-Induced Simultaneous Surface Texturing and Crystallization of a-Si:H Thin Film: Absorption and Crystallinity

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4006548 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 14

Author(s):

Hongliang Wang ◽

Panjawat Kongsuwan ◽

Gen Satoh ◽

Y. Lawrence Yao

Keyword(s):

Thin Film ◽

Solar Cell ◽

Femtosecond Laser ◽

Laser Processing ◽

Surface Texturing ◽

Solar Spectrum ◽

Nanocrystalline Silicon ◽

Femtosecond Laser Irradiation ◽

Surface Geometry ◽

Femtosecond Laser Processing

Hydrogenated amorphous silicon (a-Si:H) thin films have been considered for use in solar cell applications because of their significantly reduced cost. Their overall efficiency and stability, however, are less than that of their bulk crystalline counterparts. Limited work has been performed on solving the efficiency and stability issues of a-Si:H simultaneously. In this study, both surface texturing and crystallization on a-Si:H thin film are achieved through one-step femtosecond laser processing. The nanoscale conical and pillar-shaped spikes formed on the surface of a-Si:H films by femtosecond laser irradiation in both air and water are presented and enhanced light absorption is observed due to light trapping based on surface geometry changes, while the formation of a mixture of hydrogenated nanocrystalline silicon (nc-Si:H) and a-Si:H after crystallization suggests that the overall material stability can potentially be increased. The relationship among crystallinity, fluence, and scan speed is also discussed. Furthermore, a comparison of absorptance spectra for various surface morphologies is developed. Finally, the absorptance measurement across the solar spectrum shows that the combination of surface texturing and crystallization induced by femtosecond laser processing is very promising for a-Si:H thin film solar cell applications.

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