Antireflective disordered subwavelength structure on GaAs using spin-coated Ag ink mask

Abstract

We present a simple, cost-effective, large scale fabrication technique for antireflective disordered subwavelength structures (d-SWSs) on GaAs substrate by Ag etch masks formed using spin-coated Ag ink and subsequent inductively coupled plasma (ICP) etching process. The antireflection characteristics of GaAs d-SWSs rely on their geometric profiles, which were controlled by adjusting the distribution of Ag etch masks via changing the concentration of Ag atoms and the sintering temperature of Ag ink as well as the ICP etching conditions. The fabricated GaAs d-SWSs drastically reduced the reflection loss compared to that of bulk GaAs (>30%) in the wavelength range of 300-870 nm. The most desirable GaAs d-SWSs for practical solar cell applications exhibited a solar-weighted reflectance (SWR) of 2.12%, which is much lower than that of bulk GaAs (38.6%), and its incident angle-dependent SWR was also investigated.

Broadband antireflective silicon nanostructures produced by spin-coated Ag nanoparticles

“…To calculate the reflectance, a truncated cone-shaped Si nanostructure with a bottom diameter to period ratio of 0.8 and a top diameter to period ratio of 0.15 was assumed in order to simplify the calculations. The simulation model was constructed based on previous experimental results which used metal nanoparticles as a dry etching mask [8,11,12]. Figure  1a shows the calculated reflectance of the Si nanostructures for various periods for a fixed height of 300 nm.…”

“…It is clear that the reflectance decreased considerably with an increasing height. Although structures with taller height exhibits lower reflectance, a ‘too tall’ height is not favorable because it can cause mechanical instability [8,9]. Hence, choosing the proper height for antireflective nanostructures is necessary for practical applications.…”

“…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]. Prior to fabrication, the period- (i.e., distance between the adjacent nanostructures) and height-dependent reflection characteristics of the Si nanostructures were theoretically investigated using a rigorous coupled-wave analysis (RCWA) method in order to provide a guideline for producing a desirable Si nanostructure with broadband antireflection properties because the antireflection properties of these nanostructures are closely correlated with their geometry [6-12].…”

Fabrication of silicon solar cell with >18% efficiency using spin-on-film processing for phosphorus diffusion and SiO2/graded index TiO2 anti-reflective coating

“…In addition, anti-reflective coatings (ARCs) are commonly used to improve the efficiency of solar cells by reducing reflectivity at the airsemiconductor interface. ARCs films are generally applied using vacuum processes, such as thermal evaporation, reactive sputtering, and plasma-enhanced chemical vapor deposition, but little reported on using SOF for ARC [21][22][23][24][25][26][27][28][29][30]. The proposed SOF fabrication method is relatively inexpensive and highly scalable for large volume batch processing, making it a strong candidate for the further development of solar cells [31].…”

Recent advances in antireflective surfaces based on nanostructure arrays

“…Patterned photoresist produced by a laser-interference lithography was adopted by Song et al as etching masks to fabricate parabola subwavelength nanoarrays using an ICP etcher, and the resultant structures can significantly suppress the surface reflection in the longer-wavelength range, compared to SWSs with a cone shape 71. Dewetted Au and Ag nanostructures were also adopted as masks for dry etching to fabricate antireflective nanostructures of group III-V materials 72,73. Similar to the fabrication of silicon nanostructure arrays, close-packed or non-close-packed MCCs are frequently used as etching masks.…”