Abstracts Book - IMRC 2018

• SC4-P040
BLACK SILICON FABRICATED BY DIRECT FEMTOSECOND LASER
NANO/MICROSTRUCTURING
Anatoliy Vorobyev 1
1 Chongqing University of Posts and Telecommunications, School of Science, China.
Highly absorptive silicon is needed in many practical fields such as harvesting
solar energy, photonics, sensors, optoelectronics, and optofluidics. Previously, a
number of various techniques for reducing reflectance of silicon through
surface texturing have been developed, including wet reactive ion etching,
chemical etching, electrochemical etching, femtosecond laser-assisted chemical
etching, and direct femtosecond laser surface structuring. It has been
demonstrated that the femtosecond laser techniques are superior in producing
surface structures that dramatically decrease silicon reflectance in ultraviolet,
visible, and near-infrared wavelength ranges. Among the laser techniques, the
direct femtosecond laser nano/microstructuring is advantageous due to higher
throughput, lower cost, and absence of highly reactive chemicals. In this work,
we developed a direct femtosecond laser texturing technique for producing
black silicon with reflectance of 1.5-2.5% in the visible. Due to extremely low
reflectance the laser-treated silicon appears pitch black. The produced surface
structure is a 2D microgroove grating, the surface of which is extensively
textured with irregular nanostructures. To treat silicon, we used a femtosecond
laser system generating 100-fs laser pulses with energy of 7 mJ per pulse at 1
kHz pulse repetition rate. The laser treatment was performed in air of
atmospheric pressure. The reflectance of the laser-treated silicon was measured
using a Cary 5000 UV-Vis-NIR spectrophotometer. The produced black silicon is
mechanically robust because its surface structure is not a deposit but is
engraved on the silicon surface, rendering it suitable for operation in harsh
environments.
Keywords: Silicon, Reflectance, surface nano/microstructures
Presenting authors email: ayvzfv@gmail.com