Fabrication of highly homogeneous and controllable nanogratings on silicon via chemical etching-assisted femtosecond laser modification

Abstract

Femtosecond laser direct writing is widely exploited in surface periodic structures processing. However, this technique still faces challenges in obtaining high surface homogeneity and flexible morphology controllability. In this study, a flexible and efficient approach has been proposed to fabricate highly homogeneous and controllable nanogratings on silicon via chemical etching-assisted femtosecond laser modification. By precisely manipulating the laser-material interaction process, alternating amorphous-crystalline nanofringes are generated when employing femtosecond laser scanning over a Si sample, with almost no material removal. Following auxiliary chemical etching, highly homogeneous nanograting structures are obtained, and the morphology of the nanogratings can be flexibly managed through precisely controlling the duration of the etching process. Complex cross-scale patterns with remarkable structural colors that are visible under indoor light illumination are readily achieved on the sample surfaces exploiting our method. In addition, compared with traditional methods for laser-induced periodic surface structures, the fabrication efficiency is considerably improved. Our processing procedure offers potential applications in the fields of optics, nanoelectronics, and mechatronics.

High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse

“…The film thickness is decreased by~40 nm as a whole, and the depth between the ridges and valleys is~65 nm scanning speed, the time consumption here can be decreased by at least 4 orders of magnitude when texturing a surface area of 10 × 12 mm 2 . In addition, different from the observations of a low-spatial-frequency LIPSS reported on other materials [23][24][25][26][27] , the spatial orientation of our achieved structures is shown to be strictly parallel to the direction of the linear polarization of the incident laser ( Fig. 1d).…”

“…The FPL strategy has also been proven to be capable of breaking the diffraction limit by applying suitable experimental parameters 21,47 . Apart from this, we should also emphasize that the phenomenon here is different from others, although similar works have been covered in previous reports [23][24][25][26][27] . The spatial orientation of the grating is parallel rather than perpendicular to the polarization direction of the incident light, leading to a completely different analysis of the laser-matter interaction.…”

“…Although the first observation of laser-induced periodic surface structures (LIPSSs) can be traced back to 50 years ago 20,21 , whose universal property has been confirmed for various materials, including metals, semiconductors, and insulators, the low structural quality is obviously one of the most important factors restricting their further application. Flexible and controllable energy deposition to achieve practical structural fabrication in the subwavelength range through the FPL strategy has only been recognized in recent years [22][23][24][25][26] . The key factor in this process is the lossy and reversible nature of the plasma waves, which allows us to obtain feedback at local positions and in turn control the energy distribution to achieve the formation of regular structures 22,27 .…”

“…The conductivity of our devices has an anisotropy ratio of 0.46, which is even larger than that of some natural anisotropic crystals 35,36 . It should be noted that this is the first time that we apply the FPL strategy to the practical application of graphene analogs, not just to the usage of grating structures 25,26 . Our work combines experimental exploration with the in-depth theoretical understanding of high-speed micro/nanopatterning of regular rGO-LIPSS, which not only benefits fundamental physics but also facilitates the practical development of graphene analogs on the industrial scale [37][38][39] .…”

Spectral absorption control of femtosecond laser-treated metals and application in solar-thermal devices

“…Of interest, one-dimensional (1D) femtosecond laser-induced periodic surface structures (fs-LIPSSs) with subwavelength periodicity that can be realised on a wide range of materials have attracted considerable attention 1,2 . Different techniques have been employed to address the spatial uniformity of fs-LIPSSs, for instance, positive and negative feedback mechanisms on titanium substrates 9 , chemicalassisted fs-laser-treatment 10 , high-uniformity fs-LIPSSs creation via temporally delayed multi-pulse irradiation 11,12 , non-ablative fs-laser structuring technique 13 , or self-organisation from metal-assisted pattern formation on glass 14 . While these studies showed the ability to produce more regular surface features, they did not demonstrate the ability to design the surface properties, which is crucial at the device engineering and application level.…”