Isochronal annealing studies of carbon-related defects in irradiated Si
Introduction
Carbon is, besides oxygen, the most important impurity in Si. It has been studied intensively during the last 50 years. However, in spite of the very large amount of work that has been done so far, some aspects of its behavior, especially those concerning the reaction processes that carbon participates in, are not known in detail. Upon irradiation of carbon-rich Cz-grown Si, carbon-substitutional atoms are ejected [1] at interstitial sites , according to the Watkins-replacement mechanism . is very mobile at room temperature and it readily reacts [2] with and defects forming the and pairs, respectively. Most of the primary defects produced by the irradiation tend to annihilate between themselves , although some of them are captured by impurities present in the material , etc.) and some other pair with each other . Defect reaction modeling foresees and experiments verify [3], [4], [5] that a percentage of the 's is also captured by centers formed during the irradiation. Thus, the , the and defects act as neucleation sites for the 's and at high radiation doses, complexes as the , the and the form, as well. A pair of local vibrational mode (LVM) bands at has been correlated [2] with the , another pair at has been correlated [2] with the complex and another one at has been correlated [6] with the complex. On the other hand, vacancies are also trapped by the complexes [7] leading to the formation of the defect , through the reaction .
In neutron-irradiated , due to the spatial separation [8] of the produced vacancies and self-interstitials, complexes related to these defects form in larger concentrations. Therefore, weak signals in the spectra related to such complexes are expected to be detected more easily, facilitating their study. The purpose of this work is to study the production and evolution with temperature of the , , and defects. It is a continuation of a previous work [6], aiming in particular at throwing new light on carbon-related defects and processes, where aggregations of primary defects are involved.
Section snippets
Experimental details
Prepolished Si samples of 2 mm thickness with initial oxygen and carbon concentrations and , respectively, were irradiated with 5 MeV fast neutrons at a fluence of . The samples were wrapped in Cd foils to eliminate thermal neutrons and put inside sealed quartz boxes to avoid water contamination. After the irradiations, 20 min isochronal anneals of steps, in open furnaces were performed. After each annealing stage, infrared spectroscopy
Experimental results and discussion
Fig. 1 shows a section of the absorption spectrum of our Si samples immediately after the irradiation. By using Lorentzian profiles (Fig. 2a) it is found that the band at is the overlap of two contributing bands at 543.5 and . Figs. 2(b) and (c) exhibit the thermal evolution of the later bands. Previously IR studies [9], in electron-irradiated Si, have detected the formation of the center and six bands at 540.4, 543.3, 579.8, 640.6, 730.4 and have been attributed
Summary
We have investigated carbon-related complexes in neutron-irradiated Si, by means of IR spectroscopy. A broad band at was found to be the convolution of two bands at 543.5 and . Based on their thermal stability, we attributed these bands to the and the defects, correspondingly. The evolutions with temperature of the , and complexes were studied. Further on, a band at was tentatively attributed
Acknowledgments
This work was supported by the special account for research grants of the National and Kapodistrian University of Athens (Grant no. 70/4/3307).
References (17)
- et al.
Physica B
(2003) - et al.
Radiat. Eff.
(1970) - et al.
- et al.
Semicond. Sci. Technol.
(1987) - et al.
Semicond. Sci. Technol.
(1987) - et al.
Solid State Phenomena
(1997) - et al.
Phys. Rev. B
(2000) - et al.
J. Appl. Phys.
(2002)
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