Lithography-Free Fabrication of Large Area Subwavelength Antireflection Structures Using Thermally Dewetted Pt/Pd Alloy Etch Mask

Abstract

We have demonstrated lithography-free, simple, and large area fabrication method for subwavelength antireflection structures (SAS) to achieve low reflectance of silicon (Si) surface. Thin film of Pt/Pd alloy on a Si substrate is melted and agglomerated into hemispheric nanodots by thermal dewetting process, and the array of the nanodots is used as etch mask for reactive ion etching (RIE) to form SAS on the Si surface. Two critical parameters, the temperature of thermal dewetting processes and the duration of RIE, have been experimentally studied to achieve very low reflectance from SAS. All the SAS have well-tapered shapes that the refractive index may be changed continuously and monotonously in the direction of incident light. In the wavelength range from 350 to 1800 nm, the measured reflectance of the fabricated SAS averages out to 5%. Especially in the wavelength range from 550 to 650 nm, which falls within visible light, the measured reflectance is under 0.01%.

Broadband antireflective silicon nanostructures produced by spin-coated Ag nanoparticles

“…For this reason, the sintering temperature was carefully chosen. It is worth noting that the temperature and process time to make Ag nanoparticles is much lower and shorter, respectively, than the previously reported method in which metal nanoparticles were formed through thermal dewetting of evaporated thin metal film [7,11,12,15]. The Ag ink ratio in a mixture of Ag ink and isopropanol was adjusted to produce differently distributed Ag nanoparticles because their distribution predominantly determines the distribution of the resulting nanostructures, which strongly affects their antireflection properties [6-8,12].…”

“…To achieve this goal, nano-scale silver (Ag) etch masks were formed using spin-coating Ag ink and subsequent sintering process. The significant advantage of the reported technique is that it requires only a low temperature and a short process duration to form the Ag etch masks [ 7 , 11 , 12 ]. Furthermore, the technique avoids the usage of any lithographic process, making it highly cost-effective for mass production [ 8 ].…”

Fabrication of biomimetic patterns for high transmission and antifogging property

“…Observations on the corneas of nocturnal moths indicate that surface-relief arrays with dimension smaller than the wavelength of incident light can be an alternative to thin lm coatings, which are more stable and durable than surface coatings since only one material is involved. 34,35 This part of the light loss will cause the reduction of the transmission. SWS are usually fabricated by taking etching process with shadow masks.…”

Biomimetic corrugated silicon nanocone arrays for self-cleaning antireflection coatings

“…Bottom-up self-assembly is a simple and cost-effective alternative way to create submicrometerscale periodic arrays [13]. For example, self-assembled masks composed of colloidal nanospheres [14], metal particles [15][16][17], or an anodic porous alumina membrane [18] combined with a reactive ion etching (RIE) process have been used for the fabrication of 521 SWS surfaces. In principle, upright tapered structures with high aspect ratio that suppress reflections over a wide spectral bandwidth and AOI can be easily fabricated [18].…”