A Novel Silicon Nanotips Antireflection Surface for the Micro Sun Sensor

Abstract

We have developed a new technique to fabricate an antireflection surface using silicon nanotips for use on a micro Sun sensor for Mars rovers. We have achieved randomly distributed nanotips of radii spanning from 20 to 100 nm and aspect ratio of approximately 200 using a two-step dry etching process. The 30 degrees specular reflectance at the target wavelength of 1 microm is only about 0.09%, nearly 3 orders of magnitude lower than that of bare silicon, and the hemispherical reflectance is approximately 8%. When the density and aspect ratio of these nanotips are changed, a change in reflectance is demonstrated. When surfaces are covered with these nanotips, the critical problem of ghost images that are caused by multiple internal reflections in a micro Sun sensor was solved.

Design and fabrication of broadband ultralow reflectivity black Si surfaces by laser micro/nanoprocessing

“…22,23 There are several processing methods available for modifying the Si surface morphology. 1,5,7,[13][14][15]17,19,24,25 For example, etching methods, including chemical, electrochemical and dry etching, have been widely employed. 26,27 Dynamic etching of porous Si surfaces to a thickness of 100 nm has been demonstrated by Striemer and Fauchet, 27 who achieved an average reflection of 3.7% across the terrestrial solar spectrum.…”

Bio-Inspired Photonic Structures: Prototypes, Fabrications and Devices

“…Another fascinating application of the inspired antireflection structures is the use in the micro Sun sensor for Mars rovers [38]. On the basis of the recorded image by an active pixel sensor, the location coordinates of the rover can be calculated.…”

Enhancing light trapping of macroporous silicon by alkaline etching: application for the fabrication of black Si nanospike arrays

“…Dry etching processes such as reactive ion A c c e p t e d m a n u s c r i p t etching (RIE) or deep RIE are usually employed to fabricate grass-like nanotip arrays with broadband low reflectance. [13][14][15] In addition, the group of Mazur reported that irradiation of Si wafer with femtosecond-laser pulses in the presence of a halogen or a fluoride-containing gas can be used to create random arrays of absorbing nanocones. 16 If these dry techniques are highly tunable, their main drawbacks are their cost and the handling of gases.…”