IngentaConnect The effect of Ge implantation dose on the optical properties of G...

Authors: Mestanza, S.N.M.; Rodriguez, E.; Frateschi, N.C.

Source: Nanotechnology, Volume 17, Number 18, 28 September 2006 , pp. 4548-4553(6)

Publisher: Institute of Physics Publishing

Abstract:

Ge nanocrystallites (Ge-nc) embedded in a SiO₂ matrix are investigated using Raman spectroscopy, photoluminescence and Fourier transform infrared spectroscopy. The samples were prepared by ion implantation with different implantation doses (0.5, 0.8, 1, 2, 3 and 4) × 10¹⁶ cm^-2 using 250 keV energy. After implantation, the samples were annealed at 1000 °C in a forming gas atmosphere for 1 h. All samples show a broad Raman spectrum centred at w≈304 cm^-1 with a slight shift depending on the implantation doses. The Raman intensity also depends on the Ge⁷⁴⁺ dose.

A maximum photoluminescence intensity is observed for the sample implanted at room temperature with a dose of 2 × 10¹⁶ cm^-2 at 3.2 eV. Infrared spectroscopy shows that the SiO₂ films moved off stoichiometry due to Ge⁷⁴⁺ ion implantation, and Ge oxides are formed in it. This result is shown as a reduction of GeO_x at exactly the dose corresponding to the maximum blue-violet PL emission and the largest Raman emission at 304 cm^-1. Finally, the Raman spectra were fitted with a theoretical expression to evaluate the average size, full-width at half-maximum (FWHM) and dispersion of Ge-nc size.

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The effect of Ge implantation dose on the optical properties of Ge nanocrystals in SiO2

The effect of Ge implantation dose on the optical properties of Ge nanocrystals in SiO₂