Diffusion of germanium in silica glass

Effect of nanocavities on Ge nanoclustering and out-diffusion in SiO2

“…For an annealing duration of 60 min at 1000°C, we obtained D 1000 ∼10 −17 −10 −16 cm 2 s −1 . Such a diffusion coefficient is compatible with the data reported in the literature [10,11,13]. However, it corresponds to an average diffusion length…”

Blocking germanium diffusion inside silicon dioxide using a co-implanted silicon barrier

“…Close to the surface of the Ge/Si sample, an accumulation of Ge is clearly detected in the region containing co-implanted Si, whereas a significant decrease in the Ge concentration is reported in the Ge sample, due to Ge desorption effects. [10][11][12][13][14][15][16][17][18][19] These two features are supported by Figs Ge sample. Since the Ge atoms detected in the vicinity of the Ge/Si sample's surface are located closer than the Ge ions introduced into the SiO 2 layer, they can be associated with implanted Ge ions that have diffused towards the top of the sample.…”

“…7 Nevertheless, the design of such an architecture is very challenging for group IV nanostructured systems, notably because Si-ncs and Ge-ncs form at temperatures higher than 800 C, 8,9 for which strong thermal diffusion effects can be activated. 10,11 In particular, the arrangement of Si-ncs and Ge-ncs inside thin SiO 2 films requires the development of efficient methods that enable us to control the atom diffusion mechanisms at the nanoscale and permit the growth of nanoparticles in predetermined locations. In Ge-based fused silica glass heated to temperatures higher than 900 C, it was established that a reduction of Ge thermal diffusion is also essential to prevent Ge outgassing.…”

Inhibitive formation of nanocavities by introduction of Si atoms in Ge nanocrystals produced by ion implantation

“…Inhibitive formation of nanocavities by introduction of Si atoms in Ge nanocrystals produced by ion implantation R. S. Cai, 1 Y. Q. Wang, 1,2,a) L. Shang, 1 X. H. Liu, 1 Y. J. Zhang, 1 G. G. Ross, 3 and D. Barba 3 Germanium nanocrystals (Ge-nc) were successfully synthesized by co-implantation of Si and Ge ions into a SiO 2 film thermally grown on (100) Si substrate and fused silica (pure SiO 2 ), respectively, followed by subsequent annealing at 1150 C for 1 h. Transmission electron microscopy (TEM) examinations show that nanocavities only exist in the fused silica sample but not in the SiO 2 film on a Si substrate. From the analysis of the high-resolution TEM images and electron energy-loss spectroscopy spectra, it is revealed that the absence of nanocavities in the SiO 2 film/Si substrate is attributed to the presence of Si atoms inside the formed Ge-nc.…”

“…1,2 However, the high thermal diffusivity of Ge atoms within silica glass induces a strong Ge desorption above 1000 C, which can drastically limit the integration of Ge nanocrystals (Ge-nc) into third generation solar cells or other luminescent devices. [3][4][5] Such a feature is generally accompanied by the formation of nanocavities, which seems to be preceded by the formation of Ge-nc. 5 Although some researchers have evoked oxidization effects associated with the formation of highly mobile GeO molecules, 6 the mechanisms responsible for the Ge outdiffusion and the subsequent formation of nanocavities remain unclear.…”