Resonant energy transfer from nanocrystal Si to β-FeSi ₂ in hybrid Si/β-FeSi ₂ film

Abstract

The photoluminescence (PL) characteristics of hybrid β-FeSi2/Si and pure β-FeSi2 films fabricated by pulsed laser deposition at 20 K are investigated. The intensity of the 1.54-μm PL from the former is enhanced, but the enhancement vanishes when the excitation wavelength is larger than the widened band gap of Si nanocrystal. Time-resolved PL decay measurements reveal that the lifetime of the photo-excited carriers in the hybrid β-FeSi2/Si film is longer than that in the pure β-FeSi2 film, providing evidence that the PL enhancement results from the resonant charge transfer from nanocrystalline Si to β-FeSi2.

β-FeSi2as the bottom absorber of triple-junction thin-film solar cells: A numerical study

“…[1][2][3][4] β -FeSi 2 has a very high optical absorption coefficient (α > 10 5 cm −1 ), which is at least two orders of magnitude larger than that of crystalline silicon at 1.5 eV. [5,6] It is also compatible with the silicon-process technology. Moreover, β -FeSi 2 is an ecofriendly material because its element resources (Fe and Si) are non-toxic and abundant in the earth's crust.…”