Effect of surface roughening on femtosecond laser-induced ripple structures

Tomita, Takuro; Kinoshita, Keita; Matsuo, Shigeki; Hashimoto, Shuichi

doi:10.1063/1.2720709

Cited by 126 publications

(71 citation statements)

References 20 publications

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“…Compared with the long time duration of laser pulses, femtosecond laser-induced ripples usually have the following distinct characteristics: (i) even at the normal angle of incidence, the periodic ripple spacing can be much less than the incident laser wavelength (0.1-0.75λ laser ) [8,14,18,22]; (ii) the ripple period increases with higher laser fluences but decreases with greater cumulative pulse numbers [9,13,20,23]; (iii) both the threshold laser fluence and the available ripple period depend on the surface roughness [17,18,24,25]. Besides the classical interpretation of the optical interference, several other possible mechanisms have also been suggested by some authors [21,26,27], but none of them could sufficiently account for the abovementioned ripple features, and how to deeply understand the ripple formation by ultra-short laser pulses is still elusive, especially for the metallic materials.…”

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confidence: 99%

Creation of periodic subwavelength ripples on tungsten surface by ultra-short laser pulses

Xue

Yang

et al. 2012

Appl. Phys. A

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Formation of periodic subwavelength ripples on a metallic tungsten surface is investigated through a linescribing method under the irradiation of 800 nm, 50 fs to 8 ps ultra-short laser pulses. The distinctive features of the induced ripple structures are described in detail with different laser parameters. Experimental measurements reveal that with gradual decrease of the laser fluence, the pulse duration or the scanning speed, the ripple period is inclined to reduce but the ripple depth tends to become pronounced. Theoretical analyses suggest that the transient dielectric function change of the tungsten surface mainly originates from the nonequilibrium distribution of electrons due to the d-band transitions. A sandwich-like physical model of air-plasmatarget is proposed and the excitation of a surface plasmon polaritonic (SPP) wave is supposed to occur on the interface between the metallic target and the electron plasma layer. Formation of ripples can be eventually attributed to the laser-SPP interference. Theoretical interpretations are consistent with the experimental observations.

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confidence: 99%

Creation of periodic subwavelength ripples on tungsten surface by ultra-short laser pulses

Xue

Yang

et al. 2012

Appl. Phys. A

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“…Left and right of the square bore is a heavily damaged zone "D" only in the vicinity to the border line. The ray like appearance of this damage is perpendicular to the polarisation direction, same as the ripples created on the bottom of a bore during fs-pulse ablation [7]. We belief this ripple structure (Fig.…”

Section: Resultsmentioning

confidence: 85%

Using of laser ablation technique in the processing technology of GaN/SiC based MEMS for extreme conditions

Zehetner

Vanko

Dzuba

et al. 2014

The Tenth International Conference on Advanced Semiconductor Devices and Microsystems

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In order to improve the stability, sensitivity or efficiency of AlGaN/GaN based sensors employing high electron mobility transistors (HEMTs), Schottky diodes and/or resistors they should be integrated into micro-electro-mechanical-systems (MEMS). The creation of appropriate diaphragms and/or cantilevers is necessary for the verification of sensing properties of such MEMS sensors. In this paper, we present possible approaches to improve the fabrication of micromechanic structures in bulk SiC substrates with epitaxial AlGaN/GaN heterostructures using femtosecond laser ablation to fabricate SiC diaphragms. The objective of this work is also to point at the backside damaging effects and to find an optimal method for its elimination or suppression. IntroductionAlGaN/GaN based high electron mobility transistors (HEMTs), Schottky diodes and/or resistors have been effectively presented as sensing devices for mechanical or chemical sensors operating at extreme conditions. However, much of them were fabricated on bulk substrate materials [1], [2]. In order to improve their stability, sensitivity or efficiency, they should be integrated into micro-electro-mechanical-systems (MEMS). Therefore, the creation of appropriate diaphragms and/or cantilevers is necessary for the verification of sensing properties of such MEMS sensors. Laser ablation can fabricate SiC diaphragms much faster than electrochemical, photochemical, or reactive ion etching (RIE). Recently, we presented the possibilities to combine laser ablation technique with RIE for bulk micromachining of SiC [3]. We demonstrated the feasibility to fabricate micromechanic structures in bulk SiC substrates with epitaxial AlGaN/GaN heterostructures (Fig. 1) by femtosecond laser ablation at 520nm wavelength for pressure sensor applications [4]. Using a 300μ 4H-SiC substrate we produced an array of 250μ deep and 500μ diameter blind holes without damaging of the AlGaN/GaN heterostructures (Fig. 2). Our laser system delivered 100kHz of 350fs pulses with an average power of 950mW in the fundamental (1040nm) and 350-380mW in the second harmonic (520nm) wavelength. The 350mW output power in the SH was already the minimum power required to drill the holes down to a depth of 250μ -300μ. Therefore we made tests also with the higher laser power output at 1040nm but this led to severe damage at the backside of the substrate (Fig. 3). Consequently, we investigated "two colour laser ablation" [5] to enhance the yield and improve the machining results. An effective back side damage reduction was obtained with respect to the results when only 1040nm were used. But still the surface quality at the back side did not reach the same level as we had for ablation using only 350mW at

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“…To gain better estimate for increase of surface area, we have used laser ablation (Fig. 1) to produce laser induced periodic surface structures (LIPSS) [13][14][15][16][17][18][19][20][21][22][23] increase surface area in a controlled manner is well defined also new open questions have arisen, which we have met with our previous findings on LIPSS patterned in titanium with proteins (fibrinogen and albumin) differing in size and shape [24] . One of these open questions is the scattering of probing light beam, when interferometric or ellipsometric measurements are performed from LIPSS structures.…”

Section: Introductionmentioning

confidence: 85%

Optical resonance on LIPSS sensed by polarized light

Silvennoinen

Hasoň

Silvennoinen

2013

Eleventh International Conference on Correlation Optics

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Non-symmetric and directional reflectivity from three dimensional (3D) laser induced periodic surface structures (LIPSS) is considered. LIPSS structures were patterned in stainless steel (W720) by using linear and elliptical polarized laser beams from a femtosecond (fs) laser. The short and long periodic ripples and possible other type artifact remaining has decreasing influences to relative reflectivity variation between 5% and 65% in the wavelength range from 200nm to 800nm. The studies of patterned W720 LIPSS structures indicated, besides of increased surface area, that decrease of reflectivity is affected by light scattering from ultra-structures of LIPSS and produces resonance type differences in spectral reflectivity when either TM or TE polarized probing beam interacts with micro-and ultrastructure of LIPSS.

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Effect of surface roughening on femtosecond laser-induced ripple structures

Cited by 126 publications

References 20 publications

Creation of periodic subwavelength ripples on tungsten surface by ultra-short laser pulses

Creation of periodic subwavelength ripples on tungsten surface by ultra-short laser pulses

Using of laser ablation technique in the processing technology of GaN/SiC based MEMS for extreme conditions

Optical resonance on LIPSS sensed by polarized light

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