Open AccessFabrication of broadband anti-reflective layers by mask-free etching TiO2 films
Author(s) -
Chunliang Wang,
Xintong Zhang,
Sili Gao,
Yuguang Meng,
Akira Fujishima
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.031917
Subject(s) - materials science , optics , etching (microfabrication) , refractive index , silicon , fresnel equations , reflection (computer programming) , anti reflective coating , substrate (aquarium) , fabrication , optoelectronics , wavelength , surface finish , surface roughness , polycrystalline silicon , reactive ion etching , coating , layer (electronics) , nanotechnology , composite material , medicine , oceanography , physics , alternative medicine , pathology , geology , computer science , programming language , thin film transistor
We present a simple way to make TiO 2 anti-reflective layers on top of silicon substrates. Surfaces of TiO 2 films have been modified by radio frequency plasma with CF 4 as an etchant. Mask-free etching process on the polycrystalline films leads to the formation of random sub-wavelength textures. The reflection of the etched samples are significantly suppressed in the wavelength range of 400~800 nm (2.9~4.6%, 3% compared with 34% on bare silicon at the wavelength of 600 nm). We have numerically simulated the optical properties of TiO 2 layers using the finite-difference time-domain method. The anti-reflective effects are attributed to random roughness on TiO 2 surfaces. The etching porcess increases the surface roughness, therefore, the gradient of refractive index between air and silicon substrate is reduced. As a result, the Fresnel reflection is supressed. Our results demonstrate an efficient way of anti-reflective coating for solar cells.