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

Abstract

Ge nanocrystallites (Ge-nc) embedded in a SiO(2) 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) × 10(16) 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 Ge(74+) dose. A maximum photoluminescence intensity is observed for the sample implanted at room temperature with a dose of 2 × 10(16) cm(-2) at 3.2 eV. Infrared spectroscopy shows that the SiO(2) films moved off stoichiometry due to Ge(74+) 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.

Direct observation of quantum confinement of Si nanocrystals in Si-rich nitrides

“…Intensive studies of Ge NCs embedded in a single layer SiO 2 film have been reported by many authors, including many methods, such as magnetron sputtering of Ge and SiO 2 [57][58][59][60][61][62], oxidation of Si x Ge 1 x alloys [63], molecular beam epitaxy [64,65], Ge ion implantation [66], PECVD [67], electron beam irradiation [68], and electron beam evaporation [69].…”

Ge‐doping dependence of gamma‐ray induced germanium lone pair centers in Ge‐doped silica

“…In addition SiO 2 samples with embedded Ge nanocrystal (nc-Ge) often have an emission at ~ 3.2 eV [6][7][8][9]. This type of material is believed to be promising for micro and opto electronic applications [10][11][12] and many investigations suggest that the 3.2 eV emission is originated by a process of electron-hole recombination involving the Ge oxygen deficient defects. In particular, the GLPC that are located at the interface layers between ncGe and SiO 2 produced during the preparation of the materials seem to be involved [6][7][8][9].…”

Thermally oxidized formation of new Ge dots over as-grown Ge dots in the Si capping layer

“…One significant nanostructure, Ge QD embedded in a dielectric matrix (such as SiO 2 ) has demonstrated peculiar properties, which could potentially be used to fabricate optoelectronic, 9 photovoltaic, 10 and nonvolatile memory devices. 11 Different methods, such as oxidation of GeSi alloy films, 12 co-sputtering of Ge and SiO 2 , 13 electron beam evaporation, 14 and ion implantation, 15 have been utilized to grow the architecture of Ge QDs embedded in the SiO 2 matrix. The common structural characteristic is that the Ge QDs are randomly distributed in the SiO 2 matrix with non-uniform size.…”