Environmental photostability of SF₆-etched silicon nanocrystals

Abstract

We report on the long-term environmental stability of the photoluminescent (PL) properties of silicon nanocrystals (SiNCs). We prepared sulfur hexafluoride (SF(6)) etched SiNCs in a two-stage plasma reactor and investigated their PL stability against UV irradiation in air. Unlike SiNCs with hydrogen-passivated surfaces, the SF(6)-etched SiNCs exhibit no photobleaching upon extended UV irradiation despite surface oxidation. Furthermore, the PL quantum yield also remains stable upon heating the SF(6)-etched SiNCs up to 160 °C. The observed thermal and UV stability of SF(6)-etched SiNCs combined with their PL quantum yields of up to ~50% make them attractive candidates for UV downshifting to enhance the efficiency of solar cells. Electron paramagnetic spin resonance indicates that the SF(6)-etched SiNCs have a lowered density of defect states, both as-formed and after room temperature oxidation in air.

Gas‐Phase Plasma Synthesis of Free‐Standing Silicon Nanoparticles for Future Energy Applications

“…Overall, the external quantum efficiency of the solar cells were observed to increase from $1.5 to $13 (arbitrary units) with increased amount of Si-NPs (maximum of 50%) in the hybrid solar cells. The similarity of the results obtained from this study suggests [221] Copyright 2012, IOP Publishing. All rights reserved.)…”

“…(c) Change of the PL quantum yield from its initial value as a function of UV irradiation time in air and in N 2 ambient. (Reprinted with permission from Liptak et al Copyright 2012, IOP Publishing. All rights reserved.…”

“…In another report of Kortshagen's group, Liptak et al investigated the environmental photostability of SF 6 ‐etched Si‐NPs during non‐thermal plasma synthesis. They have observed that the optical properties of etched Si‐NPs were improved upon exposure to air, unlike the hydrogen terminated and organically functionalized Si‐NPs.…”

Nonthermal Plasma Synthesis of Nanocrystals: Fundamental Principles, Materials, and Applications

“…Nanocrystals made in this way exhibited much higher quantum yields, up to 50%. Importantly, the nanocrystals and the quantum yields were stable in air …”

Development of Co(OH)xF2−x Nanosheets for Acetone Gas Sensor Applications: Material Characterization and Sensor Performance Evaluation

“…Our FTIR analysis sheds some light on the possible influence of the SiO 2 template on retaining fluorine, as shown in Figure 6b. In the FTIR data, the sample synthesized with SiO 2 shows a strong peak at 1020 cm −1 , corresponding to bonding between Si and F, which does not decline upon annealing at elevated temperatures [30]. In contrast, the no-template sample does not show any peak at 1020 cm −1 but a large one at 650 cm −1 , which could be attributed to Co-O bonding [31].…”