A Single-Step Bottom-up Approach for Synthesis of Highly Uniform Mie-Resonant Crystalline Semiconductor Particles at Visible Wavelengths

Abstract

Optically Mie-resonant crystalline silicon nanoparticles have long attracted interest for their unique scattering behaviors. Here, we report a bottom-up nonthermal plasma process that produces highly monodisperse particles, with diameters controllable between 60 and 214 nm, by temporarily electrostatically trapping nanoparticles inside a continuous-flow plasma reactor. The particle size is tuned by adjusting the gas residence time in the reactor. By dispersing the nanoparticles in water, optical extinction measurements indicate colloidal solutions of a particle-based metafluid in which particles support both strong magnetic and electric dipole resonances at visible wavelengths. The spectral overlap of the electric and magnetic resonances gives rise to directional Kerker scattering. The extinction measurements show excellent agreement with Mie theory, supporting the idea that the fabrication process enables particles with narrow distributions in size, shape, and composition. This single-step gas-phase process can also produce Mie-resonant nanoparticles of dielectric materials other than silicon and directly deposit them on the desired substrates.

半导体纳米晶体的冷等离子体合成：原理、进展和展望

“…在多数情况下, 纳米颗粒的形状近似球形, 因为等 离子体中颗粒的生长具有准各向同性. Bapat等人 图 4 利用冷等离子体合成技术调节半导体纳米颗粒的尺寸/形状(a) [49,51] 、结晶度(b) [52] 、表面化学(c) [53,54] 和组分(d) [55] , 以实现可调变的光学 和电学性质 Figure 4 Merits of nonthermal plasma technique in modulating the size/shape (a) [49,51] , crystallinity (b) [52] , surface chemistry (c) [53,54] , and component (d) [55] of semiconductor nanoparticles (NPs) for controlled optical and electrical properties 相比硅, 锗的熔点更低(T m,Si =1687 K, T m,Ge =1211 K). 因 此, 锗纳米晶体中存在更丰富的多面体形貌.…”

Monolayer of Mie-Resonant Silicon Nanospheres for Structural Coloration

“…The crucial issue of this approach is the production of high-quality inks, in which Si NPs with a uniform size and shape are dispersed without agglomeration. Si NP inks satisfying these requirements had been hard to be produced by conventional processes such as plasma synthesis, − chemical vapor deposition, , laser ablation, ,,− and mechanical milling. , In previous work, ,,− we developed a process to produce suspensions of almost perfectly spherical Si NPs [Si nanospheres (Si NSs)] with very narrow size distributions. The suspension exhibited size-dependent vivid structural color due to the Mie resonance. ,, By mixing the suspension with an optically transparent binder such as polyvinylpyrrolidone, we produced the structural color inks and demonstrated coloration of a base material such as a PET film by painting …”

High-Temperature Anomaly in the Synthesis of Large (d > 100 nm) Silicon Nanoparticles from Hydrogen Silsesquioxane

“…The Kortshagen group modified their nonthermal plasma synthesis by creating an electrostatic potential trap in the filamentary discharge region of their plasma reactor. This encouraged particle sintering and could produce SiNPs more than 200 nm in diameter . De Marco et al used a supercritical hexane-based synthesis with trisilane and bis­(N,N′-diisopropylbutyl)­dichlorosilane .…”

“…This encouraged particle sintering and could produce SiNPs more than 200 nm in diameter. 8 De Marco et al used a supercritical hexane-based synthesis with trisilane and bis(N,N′diisopropylbutyl)dichlorosilane. 9 While this method cannot produce crystalline silicon, it allows for a wide range in particle sizes.…”