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Proceedings Paper

Nonlithographic coherent array of ultrafine particles on an irradiated material using Nd:YAG laser: influence of the laser fluence on the microstructure
Author(s): Yuji Kawakami; Eiichi Ozawa
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Paper Abstract

A non-lithographic coherent array of ultrafine tungsten particles (150-500 nm diameter) is self-assembly arranged around a laser-irradiated mark on a tungsten substrate. Single and poly-crystal tungsten substrates were irradiated by a Q-switched Nd:YAG laser under low pressure in an inert gas atmosphere. We studied the effect of the laser fluence on the morphology of the coherent arrays. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for these observations. The spacing of the coherent array increases with increasing laser fluence. For a 10.5 J/cm2 irradiation, many droplets and peeling of the surfaces induced by rapid thermal expansion of the tungsten surface were observed. The recrystallizatoin texture on the surface was also confirmed by TEM observations. This suggests that the irradiated surface layer was partially recrystallized during laser irradiation. We concluded that coherent arrays are related to the laser fluence, the crystal surface structure, and the crystal growth. The recrystallization of the slightly melted tungsten on the top surface induced by the repeated laser irradiation plays a vital role in the formation of the array. If we can produce a coherent array of ultrafine tungsten particles with a higher aspect ratio, it may have potential applications for the emission cathodes of field emission displays (FED) and microelectronic devices.

Paper Details

Date Published: 6 November 2000
PDF: 4 pages
Proc. SPIE 4088, First International Symposium on Laser Precision Microfabrication, (6 November 2000); doi: 10.1117/12.405710
Show Author Affiliations
Yuji Kawakami, Vacuum Metallurgical Co., Ltd. (Japan)
Eiichi Ozawa, Vacuum Metallurgical Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 4088:
First International Symposium on Laser Precision Microfabrication
Isamu Miyamoto; Koji Sugioka; Thomas W. Sigmon, Editor(s)

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