%) 63.2 ± 0.4 63.1 ± 0.4 Er (at.%) 1.7 ± 0.4 1.9 ± 0.4 Er (at·cm−3) 1.1 × 1021 1.3 × 1021 Si excess (at.%) Approximately 3.6 % Approximately 3.5% Figure 3 shows the 3D distributions of Si, O, and Er atoms within the reconstructed volume obtained from the APT analysis of the as-deposited layer where each dot SB203580 corresponds to one atom detected. Statistical treatment of APT data was used to quantify concentration fluctuations in the sample. Frequency distribution was compared to binomial distribution to evidence the phase separation and atom
clustering. This treatment performed on as-deposited material indicates a homogeneous spatial distribution of the three chemical species (Si, O, and Er) in the analyzed volume (41 × 41 × 88 nm3). Thus, it suggests that no Er clustering occurs during the deposition process. Moreover, selleck it is worth to note that, based on these frequency distributions, we estimate that Si-ncs or Er clusters with a diameter below 0.8 nm (corresponding to agglomerated 15 Si atoms or 10 Er atoms) could not be distinguished from free Si or Er atoms. These atomic scale investigations, correlated with the PL data (Figure 1), suggest that in the as-deposited sample, the Si sensitizers consist of less than 15 Si atoms and are efficient to excite neighboring Er3+ ions. Figure 3 3D reconstruction of the as-grown Er-doped SRSO layers of APT analysis. APT reconstruction of 3D distribution of silicon,
oxygen, and erbium atoms in the as-grown sample. The volume analyzed is 41×41×88 nm3 . Before 2003 , the standard annealing treatment, applied for the formation of Si-NCs in Si-rich SiO2 materials fabricated by different approaches, was an annealing at 1,100°C for 1 h in pure nitrogen gas. The same annealing treatment was
considered to be efficient to create the Si-NCs in Er-doped Si-rich SiO2 materials to achieve a sensitizing effect towards rare-earth ions. Figure 4 shows the 3D cluster-filtered distribution of chemical species in the Er-SRSO layers submitted to such thermal treatment. The Si-ncs are clearly seen; their density is estimated to be about (3.1 ± 0.2)×1018Si-ncs/cm3. Endonuclease The mean distance between Si-ncs, derived from their density, is found to be 6.9±0.2 nm, which is in agreement with that deduced from the 3D reconstruction. The Si-ncs are spherical in shape and are homogeneously distributed in the analyzed volume. Simultaneously, a large density of Er-rich clusters approximately (2.0×1018Er-NCs/cm3) has also been detected in the sample (Figure 4). Furthermore, some Si-ncs are interconnected by Er clusters (or channel) as illustrated in the inset of Figure 4. No particular morphology of these Er clusters has been deduced. Figure 4 3D reconstruction of the annealed Er-doped SRSO layers of APT analysis. 3D cluster-filtered distributions of chemical species (Si in red and Er in blue) in Er-doped SRSO layers annealed at 1,100°C for 1 h. For clarity, only silicon and erbium atoms which belong to clusters are represented.