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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:40 |
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Conference: Bucharest University Faculty of Physics 2010 Meeting
Section: Atomic and Molecular Physics; Astrophysics
Title:
Dangling bonds and optical properties of silicon powder
Authors:
Mircea Bercu, Vasile Bercu
Affiliation:
University of Bucharest, Faculty of Physics, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov), Romania
E-mail
vbercu@gmail.com
Keywords:
Dangling bonds, Electron spin resonance
Abstract:
This study focuses on magnetic and optical properties of silicon powder dispersed after their preparation in a liquid host of high dielectric breakdown. Paramagnetic centers population belonging especially on the surface of silicon particles have been investigated by means of EPR (Electronic Paramagnetic Resonance). The centers found at g=2.0026 corresponding to a resonance line of 6.72 G in width has been assigned to the dangling bond (DB) formatted on the particle surface. Thermal oxidation of Si powder in the range of 200 -900 0C determines the decrease to total removal of the population of the DB paramagnetic defects as a result of Si-O-Si bridge formation on the particle surface. EPR and light scattering monitor the dynamic changes produced by falling down of particles in the gravitational field to the bottom of the cuvette. The spectrometric signals were collected from a fixed part of the cuvette where the concentration of the particles decreases in time. We have found a specific EPR line at g=2.3687 when mesoscopic Si particles remain inside the sensitive volume of the couvette. Optical transitions of silicon powder according to oxidation temperatures have been related to the EPR data regarding the dangling bond population.
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