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.
Bibliographical noteFunding Information:
This work was supported in part by the Korea Science and Engineering Foundation (KOSEF) through the ASSRC at Yonsei University, basic research fund of KIST (2E15540), and the grants from KOSEF (981-0209-035-2).
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics