Silicon nanocrystal-based photonic crystal slabs with broadband and efficient directional light emission

Abstract

Light extraction from a thin planar layer can be increased by introducing a two-dimensional periodic pattern on its surface. This structure, the so-called photonic crystal (PhC) slab, then not only enhances the extraction efficiency of light but can direct the extracted emission into desired angles. Careful design of the structures is important in order to have a spectral overlap of the emission with extraction (leaky) modes. We show that by fabricating PhC slabs with optimized dimensions from silicon nanocrystals (SiNCs) active layers, the extraction efficiency of vertical light emission from SiNCs at a particular wavelength can be enhanced ∼ 11 times compared to that of uncorrugated SiNCs-rich layer. More importantly, increased light emission can be obtained in a broad spectral range and, simultaneously, the extracted light can stay confined within relatively narrow angle around the normal to the sample plane. We demonstrate experimentally and theoretically that the physical origin of the enhancement is such that light originating from SiNCs first couples to leaky modes of the PhCs and is then efficiently extracted into the surrounding.

Reappraising the Luminescence Lifetime Distributions in Silicon Nanocrystals

“…The origin of the SE luminescence decay in silicon and other semiconductor quantum dots has been heavily debated in the last two decades, and the debate has continued recently [ 10 ]. Various explanations have been proposed for the appearance of the SE in the decay dynamics, including carrier tunneling and trapping in closely spaced ensembles of nanocrystals [ 11 ], the inhomogeneously broadened size distribution [ 12 ], size-dependent electron-phonon coupling [ 10 ], and a distribution of barrier heights for non-radiative recombination [ 13 ], the latter being similar to a previous suggestion for porous silicon [ 14 ]. Clearly, knowledge of the rate distribution is required for an understanding of the luminescence mechanism in SiNCs as well as in semiconductor nanocrystals more generally.…”

Plasmon induced modification of silicon nanocrystals photoluminescence in presence of gold nanostripes

“…The above parameters can be effectively tuned in the presence of metals. This fact is interesting from the viewpoint of potential optoelectronic applications of silicon nanocrystals given that silicon nanocrystals are CMOS-compatible and exhibit room-temperature photoluminescence 4 – 10 . Understanding of the mechanisms of interaction of silicon nanocrystals with metal is of great importance for design of optoelectronic devices based on Si quantum dots such as light emitting diodes where a homogeneous metal layer plays a role of an electrode 11 – 13 .…”

Synthesis of Silica Microspheres—Inspired by the Formation of Ice Crystals—With High Homogeneous Particle Sizes and Their Applications in Photonic Crystals

“…Three-dimensional photonic crystals (PCs) have unique and complicated structures, which enable the manipulation of the flow of light [ 1 , 2 ]. Furthermore, the special dispersion properties of PCs could produce diverse fantastic, interesting, and anomalous refraction effects [ 3 , 4 , 5 ], including negative refraction [ 6 , 7 , 8 ], self-collimation [ 9 , 10 ], and a superprism effect [ 11 , 12 ]. Consequently, PCs have many important applications in various fields [ 13 , 14 ].…”