Femtosecond laser induced tunable surface transformations on (111) Si aided by square grids diffraction

Authors

Weina Han, Laser Micro/Nano-Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing
Lan Jiang, Laser Micro/Nano-Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing
Xiaowei Li, Laser Micro/Nano-Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, BeijingFollow
Yang Liu, Laser Micro/Nano-Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing
Yongfeng Lu, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2015

Citation

APPLIED PHYSICS LETTERS 107, 251601 (2015)

Comments

Copyright 2015 AIP Publishing LLC

Abstract

We report an extra freedom to modulate the femtosecond laser energy distribution to control the surface ablated structures through a copper-grid mask. Due to the reduced deposited pulse energy by changing the scanning speed or the pulse fluence, a sequential evolution of three distinctly different surface patterns with periodic distributions is formed, namely, striped ripple lines, ripple microdots, and surface modification. By changing the scanning speed, the number of the multiple dots in a lattice can be modulated. Moreover, by exploring the ablation process through the copper grid mask, it shows an abnormal enhanced ablation effect with strong dependence of the diffraction-aided fs laser ablated surface structures on polarization direction. The sensitivity shows a quasi-cosinusoid-function with a periodicity of pi/2. Particularly, the connection process of striped ripple lines manifests a preferential formation direction with the laser polarization.