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Formation of broadband antireflective and superhydrophilic subwavelength structures on fused silica using one-step self-masking reactive ion etching.

Ye X, Jiang X, Huang J, Geng F, Sun L, Zu X, Wu W, Zheng W - Sci Rep (2015)

Bottom Line: The measured antireflection properties are consistent with the results of theoretical analysis using a finite-difference time-domain (FDTD) method.This method is also applicable to diffraction grating fabrication.Moreover, the surface of the subwavelength structures exhibits significant superhydrophilic properties.

View Article: PubMed Central - PubMed

Affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900 (P.R. China).

ABSTRACT
Fused silica subwavelength structures (SWSs) with an average period of ~100 nm were fabricated using an efficient approach based on one-step self-masking reactive ion etching. The subwavelength structures exhibited excellent broadband antireflection properties from the ultraviolet to near-infrared wavelength range. These properties are attributable to the graded refractive index for the transition from air to the fused silica substrate that is produced by the ideal nanocone subwavelength structures. The transmittance in the 400-700 nm range increased from approximately 93% for the polished fused silica to greater than 99% for the subwavelength structure layer on fused silica. Achieving broadband antireflection in the visible and near-infrared wavelength range by appropriate matching of the SWS heights on the front and back sides of the fused silica is a novel strategy. The measured antireflection properties are consistent with the results of theoretical analysis using a finite-difference time-domain (FDTD) method. This method is also applicable to diffraction grating fabrication. Moreover, the surface of the subwavelength structures exhibits significant superhydrophilic properties.

No MeSH data available.


SEM images of the top view of the fused silica SWSs prepared at different CHF3 flow rates:(A) 25 sccm, (B) 30 sccm, (C) 40 sccm.
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f2: SEM images of the top view of the fused silica SWSs prepared at different CHF3 flow rates:(A) 25 sccm, (B) 30 sccm, (C) 40 sccm.

Mentions: The self-masking mechanism is primarily due to polymer deposition. To determine the elemental composition of the by-products during plasma etching, X-ray photoelectron spectroscopy (XPS) analysis was performed. XPS provides information about the elemental composition of a surface and its electron configuration. Silicon-oxygen (fused silica), carbon-oxygen (CO2), and carbon-fluorine (polymers) bonds were detected on the self-masking RIE sample surface. However, carbon-fluorine (polymer) bonds were not observed on the conventional RIE sample surface, as shown in Figure S1. Polymer deposition formation has been found to be well correlated with high concentrations of CF and CF2 radicals28. The SWSs morphology could be varied by controlling the CHF3 flow rate and etching time of the RIE process. Figure 2 shows the morphologies of SWSs etched under various CHF3 flow rates. The corresponding processing parameters are provided in Table 1. As shown in Fig. 2(A) (sample S1, average period ~80 nm), Fig. 2(B) (sample S2, average period ~100 nm), and Fig. 2(C) (sample S3, average period ~240 nm), the average period of the SWSs gradually increased with increasing CHF3 flow rate.


Formation of broadband antireflective and superhydrophilic subwavelength structures on fused silica using one-step self-masking reactive ion etching.

Ye X, Jiang X, Huang J, Geng F, Sun L, Zu X, Wu W, Zheng W - Sci Rep (2015)

SEM images of the top view of the fused silica SWSs prepared at different CHF3 flow rates:(A) 25 sccm, (B) 30 sccm, (C) 40 sccm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542686&req=5

f2: SEM images of the top view of the fused silica SWSs prepared at different CHF3 flow rates:(A) 25 sccm, (B) 30 sccm, (C) 40 sccm.
Mentions: The self-masking mechanism is primarily due to polymer deposition. To determine the elemental composition of the by-products during plasma etching, X-ray photoelectron spectroscopy (XPS) analysis was performed. XPS provides information about the elemental composition of a surface and its electron configuration. Silicon-oxygen (fused silica), carbon-oxygen (CO2), and carbon-fluorine (polymers) bonds were detected on the self-masking RIE sample surface. However, carbon-fluorine (polymer) bonds were not observed on the conventional RIE sample surface, as shown in Figure S1. Polymer deposition formation has been found to be well correlated with high concentrations of CF and CF2 radicals28. The SWSs morphology could be varied by controlling the CHF3 flow rate and etching time of the RIE process. Figure 2 shows the morphologies of SWSs etched under various CHF3 flow rates. The corresponding processing parameters are provided in Table 1. As shown in Fig. 2(A) (sample S1, average period ~80 nm), Fig. 2(B) (sample S2, average period ~100 nm), and Fig. 2(C) (sample S3, average period ~240 nm), the average period of the SWSs gradually increased with increasing CHF3 flow rate.

Bottom Line: The measured antireflection properties are consistent with the results of theoretical analysis using a finite-difference time-domain (FDTD) method.This method is also applicable to diffraction grating fabrication.Moreover, the surface of the subwavelength structures exhibits significant superhydrophilic properties.

View Article: PubMed Central - PubMed

Affiliation: Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900 (P.R. China).

ABSTRACT
Fused silica subwavelength structures (SWSs) with an average period of ~100 nm were fabricated using an efficient approach based on one-step self-masking reactive ion etching. The subwavelength structures exhibited excellent broadband antireflection properties from the ultraviolet to near-infrared wavelength range. These properties are attributable to the graded refractive index for the transition from air to the fused silica substrate that is produced by the ideal nanocone subwavelength structures. The transmittance in the 400-700 nm range increased from approximately 93% for the polished fused silica to greater than 99% for the subwavelength structure layer on fused silica. Achieving broadband antireflection in the visible and near-infrared wavelength range by appropriate matching of the SWS heights on the front and back sides of the fused silica is a novel strategy. The measured antireflection properties are consistent with the results of theoretical analysis using a finite-difference time-domain (FDTD) method. This method is also applicable to diffraction grating fabrication. Moreover, the surface of the subwavelength structures exhibits significant superhydrophilic properties.

No MeSH data available.