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Strong Confinement (strong + confinement)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

High Quality Factor Metallodielectric Hybrid Plasmonic,Photonic Crystals

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010
Xindi Yu
Abstract A 2D polystyrene colloidal crystal self-assembled on a flat gold surface supports multiple photonic and plasmonic propagating resonance modes. For both classes of modes, the quality factors can exceed 100, higher than the quality factor of surface plasmons (SP) at a polymer,gold interface. The spatial energy distribution of those resonance modes are carefully studied by measuring the optical response of the hybrid plasmonic,photonic crystal after coating with dielectric materials under different coating profiles. Computer simulations with results closely matching those of experiments provide a clear picture of the field distribution of each resonance mode. For the SP modes, there is strong confinement of electromagnetic energy near the metal surface, while for optical modes, the field is confined inside the spherical particles, far away from the metal. Coating of dielectric material on the crystal results in a large shift in optical features. A surface sensor based on the hybrid plasmonic,photonic crystal is proposed, and it is shown to have atomic layer sensitivity. An example of ethanol vapor sensing based on physisorption of ethanol onto the sensor surface is demonstrated. [source]

Whispering gallery modes in silicon nanocrystal coated microcavities

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2009
P. Bianucci
Abstract We present photoluminescence studies of silicon-nanocrystal (Si-NC) coated microcavities. The particular geometries studied are hollow fibers where there is a Si-NC coating in the inner surface and regular optical fibers and glass microspheres where the coating is on the outside surface. The coatings were prepared using an inexpensive and straightforward solution-based process that yields a high-quality film. The measured photoluminescence spectra from the resonators show high Q -factor (between 1200 and 2800) resonant modes that correspond with the whispering gallery modes expected from the confinement geometries. The presence of these modes is also an indication that the emission of the Si-NCs is coupled to the cavity. The combination of Si-NCs and optical microcavities with strong confinement has promising potential for applications like sensing, optical communications and may be a possible route toward a Si-NC laser. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

GaN/Al0.5Ga0.5N quantum dots and quantum dashes

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009
Thomas Huault
Abstract GaN/Al0.5Ga0.5N nanostructures grown on c -plane sapphire by molecular beam epitaxy using ammonia as N source have been studied. Depending on the ammonia pressure during the two dimensional , three dimensional transition of the GaN layer, the shape of the islands is strongly modified: elongated or isotropic islands are observed, leading to the formation of quantum dashes or quantum dots, respectively. This shape transition is seen as a consequence of a change in surface energy. The change of morphology of the GaN layer is clearly evidenced by photoluminescence measurements, and a large redshift in the emission peak is observed for quantum dashes as compared to quantum dots. An electric field ,3 MV/cm is estimated from the measurements at an excitation power ,20 mW/cm2. Weak photoluminescence quenching between low and room temperature for both QDs and QDashes structures is observed, indicating a strong confinement of carriers into the nanostructures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Impact of strain on scaling of Double Gate nanoMOSFETs using NEGF approach

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2008
A. Martinez
Abstract The effect of biaxial strain on double gate (DG) nanoscaled MOSFET with channel lengths in the nanometre range is investigated using Non-Equilibrium Green's Functions (NEGF) simulations. The NEGF simulations are fully 2D in order to accurately evaluate the effects of strain in strongly confined channels. Starting with a 14 nm gate length DG MOSFET with a corresponding body thickness of 9 nm we scale the transistors to gate lengths of 10, 6 and 4 nm and body thicknesses of 6.1, 2.6 and 1.3 nm, respectively. The simulated ID-VG characteristics show 11% improvement in the oncurrent for the 14 nm gate length transistor due to the , valley splitting. This improvement in the on-current is due to separate contributions from the 2 fold and 4 fold valleys to the carrier transport. However, in the device with an extreme body thickness of 1.3 nm the strain has no impact on its performance because the strong confinement itself produces a large valley splitting. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]