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UNIVERSITY OF BUCHAREST FACULTY OF PHYSICS Guest 2024-11-22 1:32 |
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Conference: Bucharest University Faculty of Physics 2015 Meeting
Section: Atomic and Molecular Physics; Astrophysics
Title: Paramagnetic centers of mechanically damaged and on porous silicon surface
Authors: Mircea BERCU, Vasile BERCU, Voicu V. GRECU
Affiliation: Faculty of Physics, University of Bucharest
E-mail mircea.bercug@gmail.com
Keywords: Paramagnetic centers , silicon surface
Abstract: This contribution investigates the paramagnetic defects related to Si-Si broken bonds produced by chemical reaction to be compared to those generated by pure mechanical treatment of the silicon surface The anodization of mono-crystallines silicon using HF and acetic acid based solutions produces porous surfaces by local removing of Si atoms, leading to the formation of hills and valleys having dimensions in the range from microns to nanometers. The Si-H coverage remaining after anodization is removed by a thermal treatment in vacuum at 850 0C and 1x10-6 torr. The second type of samples were prepared by surface scratching using a wolfram tip for locally removal of Si atoms. Both type of samples were investigated by means of Electronic Paramagnetic Resonance at room temperature in air. The EPR signal was monitored in time for all samples, revealing an anisotropic line specific to the dangling bonds. The main difference between the two type of prepared samples shows that Pb type centers were clearly observed after air exposure only in porous sample. The presence of a large strain determined by the surface porous layer was determined from the analysis of the EPR spectra corresponding to both type of samples.
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