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We report on the synthesis and characterization of CsSnI3 perovskite semiconductor thin films deposited on inexpensive substrates such as glass and ceramics. These films contained polycrystalline domains with typical size of 300 nm. It is confirmed experimentally that CsSnI3 compound in its black phase is a direct band-gap semiconductor, consistent with the calculated band structure from the first principles. The band gap is determined to be ∼1.3 eV at Γ point at room temperature. [ABSTRACT FROM AUTHOR]

We report an efficient and robust electrochemical deposition method to fabricate large-scale two-dimensional rigid arrays of metal colloids with a precise control of the particle morphology by monitoring metal growth that is confined within a templated organic porous mold. Light transmission resonances through the metallic periodic microstructures are observed and the resonance wavelengths are found to depend on the morphology of the scattering elements. Further numerical simulations confirm these transmission resonances and reveal that they are attributed to the excitations of localized or propagating surface plasmon modes supported by the specific structures. The present method of tailoring metallic microstructures could find applications in plasmonics. [ABSTRACT FROM AUTHOR]

We demonstrated a prototype of nanoelectromechanical switch which was fabricated with single-walled carbon nanotubes (SWCNTs). An alternating current electric field was utilized to assemble interconnected SWCNTs suspended over the focused ion beam lithography fabricated trenches on the electrode surface. By controlling the electromechanical coupling between the electrostatic and elastostatic forces acting on the SWCNTs, we realized the on and off states of the SWCNT switches. Both two-terminal and three-terminal measurements have been conducted and indicated repeatable switch effects. [ABSTRACT FROM AUTHOR]

The effects of size on the growth kinetics of nanowires by the vapor-liquid-solid mechanism are presented. The dependences of the growth rate and the activation energy of crystallization on size are given quantitatively. The obtained theoretical results show that the smaller the nanowire radius, the slower the growth rate, and the activation energy of crystallization will increase with decreasing radius of the nanowire. These theoretical predictions are in agreement with the experimental cases. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) integration technology using Cu interconnections has emerged as a promising solution to improve the performance of silicon microelectronic devices. However, Cu diffuses into SiO2 and requires a barrier layer such as Ta to ensure acceptable reliability. In this paper, the effects of temperature and strain normal to the interface on the inter-diffusion of Cu and Ta at annealing conditions are investigated using a molecular dynamics (MD) technique with embedded atomic method (EAM) potentials. Under thermal annealing conditions without strain, it is found that a Cu-rich diffusion region approximately 2 nm thick is formed at 1000 K after 10 ns of annealing. Ta is capable of diffusing into the interior of Cu but Cu hardly diffuses into the inner lattice of Ta. At the Cu side near the interface an amorphous structure is formed due to the process of diffusion. The diffusion activation energy of Cu and Ta are found to be 0.9769 and 0.586 eV, respectively. However, when a strain is applied, a large number of crystal defects are generated in the sample. As the strain is increased, extrinsic stacking faults (ESFs) and lots of Shockley partial dislocations appear. The density of the dislocations and the diffusion channels increase, promoting the diffusion of Cu atoms into the inner lattice of Ta. The thickness of the diffusion layer increases to 4 times the value when only a temperature load of 700 K is applied. The MD simulations demonstrated that Ta is very effective as a barrier layer under thermal loading only, and its effectiveness is impaired by tensile strain at the Cu/Ta interface. The simulations also clarified the mechanism that caused the impairment. The methodology and approach described in this paper can be followed further to study the effectiveness of barrier layers under various annealing and strain conditions, and to determine the minimum thickness of barrier layers required for a particular application. [ABSTRACT FROM AUTHOR]

We theoretically propose a design of a spaser based on spherical hyperbolic metamaterial cavities consisting of a dielectric core wrapped by several stacks of alternating layers of metal and dielectric, which can support the multipolar whispering-gallery modes (WGMs) with resonance wavelengths much larger than the cavity size. Depending on the mode order of the excited WGMs with the same angular momentum, we show that such cavities are capable of strongly confining the electric fields within different dielectric shell layers. By introducing gains into the different dielectric layers, we demonstrate that the hyperbolic cavities can act as multi-wavelength spasers with a lasing threshold as low as 811 cm-1, operating on the WGMs with the corresponding mode order. Furthermore, we also demonstrate that the slight variation on either the number of stacks or the core radius allows for easily tuning the lasing wavelengths over a wide spectral range. [ABSTRACT FROM AUTHOR]

We theoretically investigated third harmonic generation (THG) from planar chiral metamaterials consisting of a square array of gammadion-shaped metal-insulatormetal multilayered nanostructures.We showthat there exists strong circular dichroism (CD) for THG on the proposed chiral metamaterials. We also demonstrate that geometrically mirroring the gammadion -shaped meta-atoms can result in reversal of the THG-CD effect. Based on theseCDeffects in the optical nonlinear regime, we propose a design of a Fresnel zone plate (FZP) for intense focusing of theTHGsignals, in which adjacent zones of the FZP consist of gammadions with mirror symmetry and generate circularly polarizedTHGwith opposite handedness. Furthermore, we demonstrate that the relative phase of the THG can be continuously changed by rotating the gammadion around its rotational axis, which could be used in the FZP to control the polarization of the output THG signals. [ABSTRACT FROM AUTHOR]

We report experimental investigation of the photoluminescence (PL) generated from the gold nanoshells of the dielectric-metal core-shell resonators (DMCSR) that support multipolar electric and magnetic based cavity plasmon resonances. Significantly enhanced and modulated PL spectrum is observed. By comparing the experimental results with analytical Mie calculations, we are able to demonstrate that the observed reshaping effects are due to the excitations of those narrow-band cavity plasmon resonances. We also present that the variation on the dielectric core size allows for tuning the cavity plasmon resonance wavelengths and thus the peak positions of the PL spectrum. [ABSTRACT FROM AUTHOR]

We present a design of multilayer core-shell nanostructures formed by introducing a dielectric gap shell layer between a silver core and a monolayer graphene shell for spectrally selective absorption enhancement in graphene based on an unconventional Fano effect. We demonstrate that this mechanism enables great flexibility in the choice of parameters of the proposed structures for the achievement of a relatively large and narrow-band absorption enhancement in graphene. Furthermore, we also demonstrate that such a spectrally selective absorption enhancement in graphene is highly tunable and can be optimized by controlling either the core or the shell parameters. These unique absorption properties may have applications in color-selective photodetectors and image sensors. [ABSTRACT FROM AUTHOR]

Solution-processed graphene quantum dots (GQDs) possess a moderate bandgap, which make them a promising candidate for optoelectronics devices. However, negative photoconductivity (NPC) and hysteresis that happen in the photoelectric conversion process could be harmful to performance of the GQDs-based devices. So far, their origins and relations have remained elusive. Here, we investigate experimentally the origins of the NPC and hysteresis in GQDs. By comparing the hysteresis and photoconductance of GQDs under different relative humidity conditions, we are able to demonstrate that NPC and hysteresis coexist in GQDs and both are attributed to the carrier trapping effect of surface adsorbed moisture. We also demonstrate that GQDs could exhibit positive photoconductivity with three-order-of-magnitude reduction of hysteresis after a drying process and a subsequent encapsulation. Considering the pervasive moisture adsorption, our results may pave the way for a commercialization of semiconducting graphene-based and diverse solution-based optoelectronic devices. [ABSTRACT FROM AUTHOR]

We observe experimentally the spectral and spatial reshaping of fluorescence emission in dye-doped dielectric-metal core-shell resonators that support multipolar electric and magnetic-based cavityplasmonresonances. By comparing the experimental fluorescence spectra with analytical calculations based on Mie theory, we are able to demonstrate that the strong reshaping effects are the results of the coupling of dye molecules to those narrow-band cavityplasmonresonances. In addition, we show that the polarization of the fluorescence emission can also be modified by selectively coupling the molecules to the magnetic or electric based cavityplasmons. [ABSTRACT FROM AUTHOR]

We report on the experimental realization of dielectric-metal core-shell resonators with a nearly perfect metal shell layer by physically depositing metal onto the self-supporting dielectric colloids. Sharp electric and magnetic-based cavity plasmon resonances are experimentally observed, whereas increasing the metal shell thickness increases their Q-factors while narrowing their linewidths. In particular, a high Q-factor up to ~100 with a correspondingly narrow linewidth down to ~12 nm is experimentally obtained at a dipolar magnetic cavity plasmon resonance. Simulations and analytical Mie calculations show excellent agreements with the experimental results and demonstrate strong optical field confinement of such three-dimensional resonators. [ABSTRACT FROM AUTHOR]