Index-Tapered Nanostructured Films via Selective Porosification for Enhanced Light Harvesting and Environmental...

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Functionally Graded Materials (FGMs) offer continuous optical property transitions, ideal for Antireflective Coatings (ARCs).
• Existing ARCs face challenges in achieving seamless optical continuity due to limited material choices.
• Gradient Refractive-Index (GRIN) profiles are crucial for suppressing interface reflections.

Purpose of the Study:

• To develop a Seamless-GRIN ARC (SGRIN ARC) that overcomes material limitations for enhanced optical performance.
• To create a continuous refractive-index gradient from the material surface to air.
• To demonstrate the multifunctional capabilities of the SGRIN ARC in optoelectronic devices.

Main Methods:

• Atomic Layer Deposition (ALD) of AlF3, Al2O3, and intermediate AlOxFy thin films to create a continuous GRIN profile.
• Water-induced porosification of a sacrificial Al2O3 layer to extend the refractive-index gradient to air.
• Integration of the SGRIN ARC with an optical window and a 2D SnSe photodetector.

Main Results:

• Achieved an average transmittance of ~99.0% across the visible to near-infrared spectrum.
• Enhanced the photoresponse of a 2D SnSe photodetector by factors of 4.64 (365 nm), 4.78 (532 nm), and 4.63 (980 nm).
• Demonstrated moisture resistance and durability through the SGRIN structure.

Conclusions:

• The SGRIN ARC effectively suppresses reflections and enhances light harvesting.
• The developed SGRIN ARC offers a scalable strategy for next-generation optoelectronic devices.
• This multifunctional design provides environmental stability and broadband optical performance.