Abstract

The radio frequency magnetron sputtering method is used to prepare well-dispersed pyramidal-shaped Ge nanoislands embedded in amorphous SiO2 sublayers of various thicknesses. The estimated size and number density of Ge nanoislands in SiO2 sublayer thicknesses beyond 30 nm are approximately 15 nm and 1011 cm-2, respectively. Atomic force microscopy (AFM) reveals root mean square (RMS) roughness sensitivity as the SiO2 sublayer thickness varies from 30 to 40 nm. The formation of nanoislands with high aspect ratios is attributed to the higher rate of surface reactions between Ge adatoms and nucleated Ge islands than reactions associated with SiO2 and Ge. The Ge nanoisland polyorientation on SiO2 (50-nm thickness) is revealed by X-ray diffraction (XRD) patterns. Photoluminescence (PL) peaks of 2.9 and 1.65 eV observed at room temperature (RT) are attributed to the radiative recombination of electrons and holes from the Ge nanoislands/SiO2 and SiO2/Si interfaces, respectively. The mean island sizes are determined by fitting the experimental Raman profile to two models, namely, the phonon confinement model and the size distribution combined with phonon confinement model. The latter model yields the best fit to the experimental data. We confirm that SiO2 matrix thickness variations play a significant role in the formation of Ge nanoislands mediated via the minimization of interfacial and strain energies.

© 2013 Chinese Optics Letters

Size-independent low-frequency Raman scattering in Ge-nanocrystal-embedded SiO₂ films

L. Z. Liu, X. L. Wu, F. Gao, Y. M. Yang, T. H. Li, and Paul K. Chu
Opt. Lett. 35(7) 1022-1024 (2010)

Hot spot statistics and SERS performance of self-assembled silver nanoisland films

Ekaterina Babich, Sergey Scherbak, Fabrice Asonkeng, Thomas Maurer, and Andrey Lipovskii
Opt. Mater. Express 9(10) 4090-4096 (2019)

High-performance surface-enhanced Raman scattering substrate prepared by self-assembling of silver nanoparticles into the nanogaps of silver nanoislands

Jiamin Quan, Yong Zhu, Jie Zhang, Junyin Li, and Ning Wang
Appl. Opt. 56(20) 5751-5760 (2017)

High-finesse cavities fabricated by buckling self-assembly of a-Si/SiO₂ multilayers

T. W. Allen, J. Silverstone, N. Ponnampalam, T. Olsen, A. Meldrum, and R. G. DeCorby
Opt. Express 19(20) 18903-18909 (2011)

Silicon-based current-injected light emitting diodes with Ge self-assembled quantum dots embedded in photonic crystal nanocavities

Xuejun Xu, Toshiki Tsuboi, Taichi Chiba, Noritaka Usami, Takuya Maruizumi, and Yasuhiro Shiraki
Opt. Express 20(13) 14714-14721 (2012)