Gettering of Cu in self-ion irradiated silicon studied by positron annihilation spectroscopy
Abstract
The aim of this study is to prove that vacancy clusters (V x ) are effective at gettering Cu impurities in Si. The structure of V-Cu complexes in Si was determined by positron annihilation spectroscopy, namely positron lifetime, coincidence Doppler broadening, and first-principles calculation. Cu impurities were introduced by ion implantation in Si wafers in which V x were induced by Si implantation beforehand. By annealing the obtained samples, consecutive reactions between V and Cu were observed: formation of V 6Cu x complexes at 500 °C, transformation into V 2Cu y at 600 °C, and finally decomposition into V and Cu at 700 °C. Our calculations indicate that the V-Cu complexes progressively become more Cu-rich compositions with increasing temperature, as V 6Cu form at 500 °C, and transform into V 2Cu2 through to V 2Cu4 at 600 °C where the formation energy reaches the maximum.
- Publication:
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Japanese Journal of Applied Physics
- Pub Date:
- September 2019
- DOI:
- 10.7567/1347-4065/ab352c
- Bibcode:
- 2019JaJAP..58i6501M