Affiliation: | a Department of Physics, Atomic-scale Surface Science Research Center, Yonsei University, Seoul 120-749, South Korea b Department of Metallurgical Engineering, Yonsei University, Seoul 120-749, South Korea c Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 130-650, South Korea |
Abstract: | Ge ions were implanted at 100 keV with 3×1016 cm−2 into a 300 nm thick SiO2 layer on Si. Visible photoluminescence (PL) around 2.1 eV from an as-implanted sample is observed, and faded out by subsequent annealing at 900°C for 2 h. However, PL shows up again after annealing above 900°C at the same peak position. Compared with the as-implanted sample, significant increase of Ge–Ge bonds is measured in X-ray photoelectron spectroscopy, and the formation of Ge nanocrystals with a diameter of 5 nm are observed in transmission electron microscopy from the sample annealed at 1100°C. We conclude that the PL peak from the sample annealed above 900°C is caused by the quantum confinement effects from Ge nanocrystals, while the luminescence from the as-implanted sample is due to some radiative defects formed by Ge implantation. |