Browsing by Author "Chang, Cho-Wei"

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Sapphire surface patterning using femtosecond laser micromachining
(2012-11-01)
Chang, Cho-Wei
;
Chen, Chien-Yu
;
Chang, Tien-Li
;
Ting, Chia-Jen
;
Wang, Chien-Ping
This study presents an alternative method for micron-resolution patterning of a sapphire surface utilizing the characteristic of an ultra-short pulse (10(-15) s) from ytterbium (Yb) femtosecond laser (FS-laser) irradiation. Conventional processes often involve several steps, such as wet chemical or dry etching, for surface structuring of sapphire. In this study, two-dimensional array patterns on the sapphire surface with an area of 5x5 mm(2) and a depth of 1.2 +/- 0.1 mu m can be directly and easily fabricated by a single step of the FS-laser process, which involves 350-fs laser pulses with a wavelength of 517 nm at a repetition rate of 100 kHz. The measured ablation depths on the sapphire surface display that the proposed process can be under well-controlled conditions. Based on the design changes for being quickly implemented in the micromachining process, a FS laser can be a promising and competitive tool for patterning sapphire with an acceptable quality for industrial usage.
Study of Metals by Femtosecond Laser Processing for Electro-Optics Applications
(2012)
Chang, Cho-Wei
;
Chang, Tien-Li
;
Tsai, Ting-Kai
;
Ting, Chia-Jen
;
Wang, Chien-Ping
Femtosecond laser (FS-laser) microstructuring of metals has become a promising tool because of its non-contact nature, which allows the micromachining and direct processing of materials with a minimized volume of heat-affected zone for electro-optics applications such as light emitting diodes (LED) and solar photovoltaic (PV) lighting. This study presents ultra-short pulse (10(-15) sec) FS-laser processing. Through integrating the laser source, optical system and dynamic control modules, the materials of metals with micro-scale or nano-scale structures can be fabricated. In traditional processing such as semiconductor processing, development, exposure and etching necessitate expensive equipment and time-consuming tasks. With FS-laser processing, high-precision patterns are obtained, which will be a great benefit to keeping costs down. In this study, the wavelengths of FS-laser ablation are employed using visible and infrared light. To make a breakthrough in electro-optics processes, the CIGS thin-film of solar cells in metal process can be easily produced by the FS-laser. The ablation speed of the FS-laser for thin film layer CIGS solar cells can reach 2000 mm/s which is faster than the current Nd:YAG laser machine (similar to 1000 mm/s). On the other hand, the minimum size of metal lines can be controlled to a value that is lower than 40 mu m. Furthermore, green energy can be effectively developed for the future.