ISSN:
1662-8985
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Excimer lasers have been utilized for the crystallization of hydrogenated amorphoussilicon for electronic applications. These lasers typically operate in the ultraviolet and hence photonsare absorbed by the silicon thin films within a few nanometres of the surface, melting andsolidifying the silicon on a nanosecond timescale, often without affecting the underlying substrate.This technique enables the use of inexpensive substrates, such as glass, which are highly preferablefor low cost, large-area electronic devices. The depth of crystallization becomes important forapplications such as photovoltaics, which depends on a number of factors; with laser beam shapeone of the most significant. A Gaussian beam profile has been reported to be best suited forcontrolled evolution of hydrogen during crystallization with minimum surface damage. Previousreports show the typical energy densities of crystallization, comparing the crystalline volume andsurface roughness of the resultant films for different film thicknesses. We report significantreductions of laser energy densities for crystallization by modifying the Gaussian pulse profile,while retaining the controlled evolution of hydrogen from hydrogenated amorphous silicon films.An asymmetrical, shorter pulse profile retains the desirable gradual leading edge of the Gaussianpulse for controlled evaporation of hydrogen, while increasing the peak energy. The resultant filmsshow increased surface roughness along with higher crystalline volumes, which may be beneficialfor photovoltaics
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.31.185.pdf
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