A review of cost-effective black silicon fabrication techniques and applications

Abstract

Ever since the discovery of black silicon, scientists have been trying to come up with novel methods of utilizing this material in a variety of different industries due to its low reflectivity and excellent electronic and optoelectronic properties.

Dewetting-Assisted Patterning: A Lithography-Free Route to Synthesize Black and Colored Silicon

“…When structured into vertically aligned Si nanowires (VA-SiNW) arrays, Si can sustain a variety of optical resonances, such as Fabry-Pérot and Mie resonances, and leaky waveguide modes. − Such VA-SiNW arrays can give rise to functional silicon surfaces with vibrant colors, , providing an elegant path toward the fabrication of “colored silicon”, investigated for optical sensing, and the manufacture of color filters . Additionally, the high reflectance of bulk silicon surfaces can be suppressed down to a few percent using structured black Si, which is highly relevant for solar conversion systems: ,− For example, nonuniform black VA-SiNWs films were used as an antireflection coating with a high angular acceptance to improve the efficiency of state-of-the-art silicon solar cells built with interdigitated back-contacts. , Instead, properly nanostructured colored silicon could be used as a wavelength selective absorption layer to produce silicon solar cells with well-defined and vivid colors. Although yet unexplored, such colored silicon could provide another path to engineer the aesthetics of silicon solar cells for colored photovoltaics. , Since the optical properties of both black and colored silicon are strongly geometry dependent, finding cost-effective methods to reliably nanostructure silicon is essential.…”

“…Thanks to its high abundance, optimum band gap for solar absorption and tunable electronic properties, silicon has been the material of choice for essential technologies in microelectronics and photovoltaics. , Nanostructuring silicon provides unique properties with potential applications in electronics, photonics, − sensing, − energy storage , and conversion, ,− and nanomedicine . When structured into vertically aligned Si nanowires (VA-SiNW) arrays, Si can sustain a variety of optical resonances, such as Fabry-Pérot and Mie resonances, and leaky waveguide modes. − Such VA-SiNW arrays can give rise to functional silicon surfaces with vibrant colors, , providing an elegant path toward the fabrication of “colored silicon”, investigated for optical sensing, and the manufacture of color filters .…”

“…The fabrication of VA-SiNW arrays can be achieved via bottom-up vapor–liquid solid (VLS) synthesis and top-down techniques such as reactive-ion etching (RIE) , and metal-assisted chemical etching (MACE). ,, While VLS can suffer from charge recombination using the conventional gold catalyst, RIE yields surface damage and requires expensive instrumentation that is not accessible to every research groups . Instead, MACE has appeared as a versatile, benchtop, solution-phase and cost-effective alternative to structure silicon. ,,,, MACE uses a nanostructured catalytic metal mask, usually made of gold, to etch through silicon: When immersed into an HF/H 2 O 2 solution, the gold film catalyzes H 2 O 2 reduction, injecting holes through the metal/Si Schottky barrier and oxidizing Si that dissolves in presence of HF . Due to the high reactivity of gold toward the reduction of H 2 O 2 , MACE is highly selective: only the silicon in direct contact with the metal is etched.…”

NO2 Gas Sensor Based on Pristine Black Silicon Formed by Reactive Ion Etching

“…The so-called "black Si" (BSi) or "Si grass" is a nanostructured layer of crystalline Si consisting of thin high-density nanoneedles. [23][24][25][26] The presence of needles gives this material a darkened black hue, hence its name. In the literature, BSi is often characterized as a variety of PSi.…”

“…Experimental comparison of these methods in the manufacturing of solar cells and integrated circuits shows that RIE is one of the most significant methods owing to its excellent repeatability, reliability, safety, controllability, low cost, and large-area capability. [24][25][26] In addition, RIE is a self-organized, single-step process independent of the crystal orientation. It can be used for polycrystalline Si and is compatible with the photolithography process.…”