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Identifier uch.physics.msc//2004zorba
Title Ανάπτυξη μικροακίδων πυριτίου με laser
Alternative Title Laser induced Si Micro-spikes fabrication
Creator Zorba, Vasilia
Abstract Cumulative laser irradiation of silicon wafers in a reactive gas atmosphere is known to give rise to the formation of dense arrays of high aspect ratio silicon (Si) micro-pyramids (spikes). This work examines the possibility of controlling the tip radius and aspect ratio of the obtained structures achieved by optimizing the laser and ambient gas pressure (SF6) conditions. In particular, Si spikes were grown by using lasers of different wavelength and pulse duration. A comparative study between ns (XeCl, 308nm) and fs (Ti:Sap., 800nm; KrF, 248nm) laser sources is presented. The obtained conical Si features exhibited a rather homogenous distribution and a spontaneous self-alignment into arrays. Their tip diameter was down to 500nm while their height reached up to 30 μm. When tested as cold cathode field emitters these structures showed a field emission threshold as low as 2 V/μm, with an emission current of 10-3 A/cm2 at 4 V/μm. Even though these structures have smaller aspect ratios than good quality carbon nanotubes, their field emission properties are similar. The simple and direct formation of field emission Si arrays over small preselected areas by laser irradiation could lead to a novel approach for the development of electron sources.
Issue date 2004-07-01
Date available 2004-09-17
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/6/4/9/metadata-dlib-2004zorba.tkl Bookmark and Share
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