Formation of silicon nanocrystals by laser processing of silicon rich oxides

buir.advisorAydınlı, Atilla
dc.contributor.authorGündoğdu, Sinan
dc.departmentDepartment of Physicsen_US
dc.descriptionAnkara : The Department of Physics and the Graduate School of Engineering and Science of Bilkent University, 2012.en_US
dc.descriptionThesis (Master's) -- Bilkent University, 2012.en_US
dc.descriptionIncludes bibliographical references leaves 77-81.en_US
dc.description.abstractSilicon nanocrystals are well known to exhibit strong luminescence in the visible. Extension of this into a nanocrystal network would be beneficial for many applications. In the light of recent advances on exciton-plasmon interactions and photovoltaic cells, there is renewed interest in the use of nanostructures. Due to quantum confinement, silicon nanoclusters with increased band gaps, are promising for down conversion light and enhanced emission on plasmonic surfaces. Conventional techniques utilize high-temperature processing to obtain the Si-SiO2 phase separation which uses high thermal budget, not suitable for localized applications not compatible with glass substrates or thin-film stacked structures. An alternative approach capable of avoiding high temperature processing is laser irradiation of substochiometric amorphous silicon oxides. In this work, continuous-wave laser processing of Si-rich oxide thin films with varying Si content were performed in order to obtain Si nanocrystals embedded in silica. The role of composition, dwell times and power densities were investigated for Si-SiO2 phase separation. We present cw laser processing of PECVD grown and sputtered SiOx films. XPS, RBS and ERDA techniques were used for the stoichiometry analysis of different composition as grown samples and their optical properties were determined through ellipsometry analysis. Processing was performed with an Ar+ laser at 488 nm. The structural changes due to processing were investigated by Raman and photoluminescence spectroscopy. It has been shown that silicon nanocrystals formation depends both on precursor gas composition (hydrogen-diluted SiH4 and N2O or CO2 gases) and on laser power density. PECVD grown hydrogenated SiOx films were compared with sputtered films with and without hydrogen to identify the role of hydrogen for phase separation.en_US
dc.description.provenanceMade available in DSpace on 2016-01-08T18:24:51Z (GMT). No. of bitstreams: 1 0006506.pdf: 4421910 bytes, checksum: 965ca588bb8f92828062a89c135c119d (MD5)en
dc.description.statementofresponsibilityGündoğdu, Sinanen_US
dc.format.extentxv, 88 leaves, illustrations, graphicsen_US
dc.publisherBilkent Universityen_US
dc.subjectsilicon rich oxidesen_US
dc.subjectthin filmen_US
dc.subjectlaser anealingen_US
dc.subject.lccTA418.9.T45 G85 2012en_US
dc.subject.lcshThin films.en_US
dc.titleFormation of silicon nanocrystals by laser processing of silicon rich oxidesen_US
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