Silicon‐Based Dielectric Metamaterials: Focus on the Current Synthetic Challenges

Abstract

Metamaterials have optical properties that are unprecedented in nature. They have opened new horizons in light manipulation, with the ability to bend, focus, completely reflect, transmit, or absorb an incident wave front. Optically active metamaterials in particular could be used for applications ranging from 3D information storage to photovoltaic cells. Silicon (Si) particles are some of the most promising building blocks for optically active metamaterials, with high scattering efficiency coupled to low light absorption for visible frequencies. However, to date ideal Si building blocks cannot be produced by bulk synthesis techniques. The key is to find a synthetic route to produce Si building blocks between 75-200 nm in diameter of uniform size and shape, that are crystalline, have few impurities, and little to no porosity. This Review provides a theoretical background on Si optical properties for metamaterials, an overview of current synthetic methods and gives direction towards the most promising routes to ideal Si particles for metamaterials.

New Self‐Organization Route to Tunable Narrowband Optical Filters and Polarizers Demonstrated with ZnO–ZnWO4 Eutectic Composite

“…Other bottom‐up methods which were utilized to manufacture novel optical materials include: colloidal chemistry, self‐assembled nanoparticle clusters, use of liquid crystals, laser‐induced self‐organization, use of anodized alumina templates, block copolymers, silicon‐based dielectric metamaterials, nanoparticles aligned in porous matrices, or a bottom‐up nanolithography …”

Designing “Metamolecules” for Photonic Function: Reduced Backscattering

“…Special optical properties, including a negative refractive index, large absorption cross‐sections, and small backscattering, [ 1–3 ] make metamaterials desirable for many applications such as creating invisibility cloaks, enhanced sensors, and nanolasers and solar energy collection. [ 2,4–10 ] Metasurfaces are readily fabricated by top‐down lithography. [ 4,5 ] However, the grain boundaries and defects within the resulting nanostructures cause greater damping and concomitantly impair their optical properties.…”

Effect of solvent on silicon nanoparticle formation and size: a mechanistic study

“…Silicon has exceptional optical properties spanning from photoluminescence to Mie resonance, which has generated frenetic activity among physicists in recent years. 1 Silicon is an abundant and nontoxic element, thus commercial applications are expected from optically active biomedical probes to telecommunications. [1][2][3] One particularly exciting application is the prospect of forward-light scattering, which can be used for beam shaping.…”

“…1 Silicon is an abundant and nontoxic element, thus commercial applications are expected from optically active biomedical probes to telecommunications. [1][2][3] One particularly exciting application is the prospect of forward-light scattering, which can be used for beam shaping. In pursuit of optical metamaterials, large particle diameters, that is ≥75 nm, are required.…”

“…In pursuit of optical metamaterials, large particle diameters, that is ≥75 nm, are required. 1 It is especially difficult to grow nanoparticles larger than 10 nm using solution chemistry. The size restriction can be attributed to the sluggish particle growth kinetics compared to nucleation rate.…”