title: 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.
authors.affiliation: Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA. lipt0010@umn.edu
authors.forename: R W
authors.initials: RW
authors.lastname: Liptak
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: N J
authors.initials: NJ
authors.lastname: Kramer
authors.forename: U
authors.initials: U
authors.lastname: Kortshagen
authors.forename: S A
authors.initials: SA
authors.lastname: Campbell