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Observation of defects in g - irradiated Cz-si annealed under high pressure
|Krzysztof Wieteska 1, Wojciech Wierzchowski 2, Andrzej Misiuk 3, M. Prujszczyk 3, Ivana Capan 4, Deren Yang 5, Walter Graeff 6
1. Institute of Atomic Energy, Otwock-Świerk 05-400, Poland
Samples cut out from Czochralski grown silicon crystals (Cz-Si) including those doped either with nitrogen to 1.2x1015 cm-3 or with germanium to 7x1017 cm-3, were subjected to different thermal and pressure treatments before and after irradiation with high intensity g - rays of 60Co, up to 2350 MRad. The pre-irradiation treatment was performed for 5 h at 800oC, 1000oC, or 1130oC under atmospheric or high argon pressure (HP, up to 11 kbar). The post implantation treatment was performed at room temperature or 1000oC under atmospheric pressure or HP. The reference, not irradiated Cz-Si crystals were also studied. It has been expected that the irradiation can generate a nucleation centres for the formation of oxygen precipitates, while the presence of nitrogen or germanium usually moderates this process.
The creation of defects in the samples was investigated by means of various synchrotron X-ray diffraction methods including observation of the rocking curves, monochromatic beam topography and by several topographic methods using white synchrotron white beam. The experiments were performed at E2 and F1 experimental stations in HASYLAB. In the present case a very important method was the Bragg - case section topography, realised using 5 mm narrow slit, which allows to indicate the presence of small and not well resolved inclusions and to evaluate the perfection of the sample better than other X-Ray methods.
It was found that, in case when the initial treatment was performed at up to 1000oC, the effect of irradiation and of the treatments was not very distinct, and similar for different samples. In the case of the highest pre - irradiation treatment temperature applied (1130oC), we observed the formation of characteristic inclusions. These inclusions were usually of lower concentration and better resolved in the nitrogen - or germanium - doped samples.
The observed effects are related to enhanced radiation hardness of Cz-Si doped with germanium or nitrogen in comparison to that of non doped material (compare ).
 A. Misiuk, B. Surma, C.A. Londos, J. Bak-Misiuk, W. Wierzchowski, K. Wieteska, W. Graeff „Oxygen precipitation and creation of defects in neutron irradiated Cz-Si annealed under high pressure” physica status solidi c 2 (6) (2005) 1812-1816
Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Wojciech Wierzchowski
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth
Submitted: 2007-01-22 18:18 Revised: 2009-06-07 00:44