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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:33 |
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Conference: Bucharest University Faculty of Physics 2013 Meeting
Section: Atomic and Molecular Physics; Astrophysics
Title:
Paramagnetic Centers of Oxidized Porous Silicon Surface
Authors:
Mircea Bercu
Affiliation:
University of Bucharest , Faculty of Physics , Atomistilor 405, Bucharest –Magurele,
Romania, PO-Box MG-11, RO-77125
E-mail
mircea_bercu@yahoo.com
Keywords:
paramagnetic centers, nano-porous surface
Abstract:
Paramagnetic centers produced by oxidation of porous silicon (PS) at temperature in the range of 400C - 5500C were investigated by means of X band EPR (Electron Paramagnetic Resonance). The ratio of Si-H to Si-O groups was monitored by the corresponding infrared absorption band integral intensities to be correlated to EPR signal given by paramagnetic defects. Both vacuum dehydrogenated (800 0C) PS samples and those with large Si-H surface coverage were investigated. In the first case the evolution of EPR spectrum starts from an almost isotropic resonance at g=2.005 changing up to one of axial symmetry (gII||=2.002 and g„¨=2.008), after PS oxidation at temperatures above 2000C. Three stages of paramagnetic centers formation were determined, corresponding to surface oxidation process and to the relaxation of the accumulated strain of Si-SiO2 structure.
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