Bulk photovoltaic effect in photoconductive metamaterials based on cone-shaped nanoparticles

Abstract

Photoelectric properties of metamaterials comprising asymmetrically shaped, similarly oriented metallic nanoparticles embedded in a homogeneous semiconductor matrix are theoretically and numerically studied. The asymmetric shape of the nanoparticles is found to result in the existence of a preferred direction where "hot" photoelectrons are emitted from the nanoparticle surface under the action of the localized plasmonic resonance excited in the nanoparticles. The resulting directional photocurrent flow occurring when nanoparticles are uniformly illuminated by a homogeneous plane wave is the direct analogy of the photogalvanic effect known to exist in naturally occurring non-centrosymmetric media. This plasmonic bulk photovoltaic effect is intermediate between the inner photoelectric effect in bulk media and the outer photoelectric effect at macroscopic interfaces. The results obtained are valuable for characterizing photoemission and photoconductive properties of plasmonic nanostructures. They can find many uses for photodetection-related and photovoltaic applications.

Electron photoemission in plasmonic nanoparticle arrays: analysis of collective resonances and embedding effects

“…For nanoparticles completely surrounded by a homogeneous medium with refractive index n s and under normal incidence of light, these wavelengths λ RA (mx,my) are determined by [40] (2) In dense lattices [7,16], where a x , a y < 2πc/(n s ω LSPR ), all of the RA wavelengths (2) are far away from the LSPR wavelength range λ ~ λ LSPR , so resonant effects related to the individual-particle LSPR dominate (although it should be mentioned that λ LSPR in such an array is slightly different from λ LSPR of an isolated nanoparticle [41,42], this deviation is minor and will not be considered). However, if the lattice constants become larger so that λ RA (mx,my) approach λ LSPR =2πc/ω LSPR , it is known that collective lattice resonances become pronounced and bring about enhanced narrow-band absorption and photoemission [38]. In particular, it makes sense to study a rectangular nanoparticle lattice with a x > a y (Fig.…”

“…Such a chain array is somewhat akin to a metal strip grating, and is known to exhibit narrow plasmonic resonances. From the polarization properties of the short-range and long-range terms in the dipole radiation of the nanoparticles [26,28], stronger and narrower plasmonic resonances are expected for the y-polarization of incident light [38].…”

“…For reference, we begin by briefly reviewing our earlier results where the nanoparticle array is fully surrounded by GaAs [38]. The calculated absorption spectra are shown in Fig.…”

“…One recent example is the work of Sobhani et al [11], again based on metal-strip gratings, where narrowband photodetection can be spectrally tuned by varying the grating pitch. Another example is our earlier work [38] involving an array of nanoparticles completely embedded in semiconductor. It was shown that interaction between a narrow-band lattice resonance, namely the Rayleigh anomaly, and a broader-band localized surface plasmon resonance of individual particles brings about a tunable, narrow-band, Fanoshaped peak in spectral photoemission response.…”

Surface and volume photoemission from metal nano-particles with electron mass discontinuity

“…General approach for SPE in metal nanoparticles, taking into account discontinuities in electromagnetic field and electron effective mass is given in [13] following the description of SPE by quantum theory of periodic perturbations in continues spectrum [1,2]. The approach and results of [13] have been used, in particular, for studies of electron photoemission from plasmonic nanoantennas [12], comparison between surface and volume photoelectric effects in the internal photoemission from plasmonic nanoparticles [15], broadening of plasmonic resonance due to electron collisions with nanoparticle boundary [16] and enhanced electron photoemission by collective resonances in the nanopartical lattices [17].…”