UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2017 Meeting


Section: Solid State Physics and Materials Science


Title:
Paramagnetic defects produced by high radiation doses of 3.5 MeV and 27 MeV in silicon detector material


Authors:
Alexandra Camelia JOITA (1,2), Sergiu Vasile NISTOR (1,2)


*
Affiliation:
1) National Institute of Materials Physics, Atomistilor 405A, Magurele-Ilfov, 077125 Romania.

2) Faculty of Physics, University of Bucharest, Magurele-Ilfov, 077125 Romania.



E-mail
alexandra.joita@infim.ro


Keywords:
crystalline silicon, ESR spectroscopy, high radiation doses, irradiation paramagnetic point defects


Abstract:
To improve the radiation hardness of the silicon detectors [1] used in collision experiments it is important to understand the radiation damage mechanisms at high radiation doses, to identify the resulting irradiation paramagnetic point defects (IPPDs). We need to know the structure, formation, transformation and stability of the resulting IPPDs with a direct impact on the detector performance. To this purpose we investigated by Q-band (34 GHz) electron spin resonance (ESR) spectroscopy, from room temperature down to 20K, samples of ultra-high purity, n-type (3-4 kohm.cm), single crystalline silicon grown by floating zone technique irradiated with 3.5MeV and 27MeV. Anisotropic ESR spectra were observed before and after isochronal annealing of 30 minutes, in steps of 50oC, in the 150 - 300oC temperature range. The ESR spectra recorded at low and high microwave power levels, with the magnetic field in a (110) plane, where quantitatively analyzed and resulted in the identification of several IPPDs, characterized by specific spin Hamiltonian parameters and local symmetry [2]. Differences in the IPPDs production with irradiating electrons energy are observed and discussed.


References:

[1] I. Pintilie G. Lindstroem, A. Junkes, E. Fretwurst, Nucl. Instr. & Meth. in Phys. Res. A 611, 52 (2009)

[2] I. Pintilie, L.C. Nistor, S.V. Nistor, A.C. Joita, „Experimental techniques for defect characterization of highly irradiated materials and structures”, in The 25th International workshop on vertex detectors, Proceedings of Science,

https://pos.sissa.it/cgi-bin/reader/contribution.cgi?id=287/033