Fundamentals of ultrafast laser–material interaction

Shugaev, Maxim V.; Wu, Chengping; Armbruster, Oskar; Naghilou, Aida; Brouwer, Nils; Ivanov, Dmitry; Derrien, Thibault J.-Y.; Bulgakova, Nadezhda M.; Kautek, Wolfgang; Rethfeld, Baerbel; Zhigilei, Leonid V.

doi:10.1557/mrs.2016.274

Cited by 214 publications

(101 citation statements)

References 63 publications

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“…Ultrashort laser pulses are an essential tool in medical and industrial applications. [1][2][3][4][5][6][7][8] The development of modern lasers allows for shorter and shorter pulse durations. For material processing, generally applicable descriptions of the energy dissipation in a strongly excited material are needed, valid for a large variety of laser parameters and sample sets [9][10][11][12][13][14] .…”

Section: Introductionmentioning

confidence: 99%

Phonon-induced long-lasting nonequilibrium in the electron system of a laser-excited solid

Weber

Rethfeld

2019

Phys. Rev. B

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Electron-electron thermalization and electron-phonon relaxation processes in laser-excited solids are often assumed to occur on different timescales. This is true for the majority of the conduction band electrons in a metal. However, electron-phonon interactions can influence the thermalization process of the excited electrons. We study the interplay of the underlying scattering mechanisms for the case of a noble metal with help of a set of complete Boltzmann collision integrals. We trace the transient electron distribution in copper and its deviations from a Fermi-Dirac distribution due to the excitation with an ultrashort laser pulse. We investigate the different stages of electronic nonequilibrium after an excitation with an ultrashort laser-pulse of 800 nm wavelength and 10 fs pulse duration. Our calculations show a strong nonequilibrium during and directly after the end of the laser pulse. Subsequently, we find a fast thermalization of most electrons. Surprisingly, we observe a long-lasting nonequilibrium, which can be attributed to the electron-phonon scattering. This nonequilibrium establishes at energies around peaks in the density of states of the electrons and persists on the timescale of electron-phonon energy relaxation. It influences in turn the electron phonon coupling strength. * weber@physik.uni-kl.de 1 A. Vogel and V. Venugopalan, Chemical Reviews 103, 577

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Section: Introductionmentioning

confidence: 99%

Phonon-induced long-lasting nonequilibrium in the electron system of a laser-excited solid

Weber

Rethfeld

2019

Phys. Rev. B

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“…Once the electrons are released, they are accelerated by the laser field and collide with the other atoms and electrons in the surrounding area, releasing more ions and electrons in a chain reaction. In this process, the rapid evaporation and expansion of materials may generate powerful shock waves, and laser plasma is generated in most cases . Thus, laser‐induced plasma is a phenomenon that appears in the process of energy delivery to the target surface in a very short time using an intense laser pulse.…”

Section: Resultsmentioning

confidence: 99%

Pulsed‐Laser‐Induced IR Stereoscopic Imaging

Pak

Jeong

Lim

et al. 2019

Advanced Optical Materials

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Research on displays that can provide stereoscopic information for advertising, education, medical applications, and military simulations is on the rise. Because IR images are invisible to human eye, they can be used when security or privacy is required. If stereoscopic image display techniques are extended from the visible region to the IR region, they are able to provide more or selective information to humans. Therefore, a method of using laser beam steering to form IR stereoscopic images on a plain substrate is investigated in this study. A technique is developed for displaying IR stereoscopic images that can be detected by using an IR thermal imaging camera (ITIC), while remaining invisible to the human eye. This approach can be used to represent various IR patterns due to plasma generated during laser irradiation of the glass substrate. Static IR images are produced with stereoscopic contours: point‐shaped laser‐beam spots are connected to form IR‐emitting lines, and the IR‐emitting lines are further arranged to form IR‐emitting faces. IR stereoscopic video images with perspective are implemented by sequentially displaying time‐variant IR static images controlled by laser beam steering. Full‐color‐image representation on an ITIC is achieved using laser beam steering and the laser pattern formation method.

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“…The short pulse laser results in increased direct ablation of the SiN x with only a small surface region of the Si being thermally‐melted by the laser process . Importantly from the perspective of increased adhesion, the short pulses cause the formation of laser‐induced periodic surface structures (LIPSS) on the exposed Si surface after SiN x ablation (see Figure ) which can act to increase the adhesion of plated metal.…”

Section: Challenges For Copper‐plated Silicon Solar Cellsmentioning

confidence: 99%

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

Lennon

Colwell

Rodbell

2018

Progress in Photovoltaics

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Copper‐plated interconnects were widely adopted for volume manufacture of integrated circuits after more than a decade of intensive research to demonstrate that use of Cu would not impact device reliability. However, although Cu‐plated metallisation promises significantly reduced costs for Si photovoltaics, its adoption in manufacturing has not gained the same traction. This review identifies some key challenges facing the introduction of Cu‐plated metallisation for Si photovoltaics. These include the following: (1) increased carrier recombination due to the use of Cu for metal contact formation; (2) reduced module reliability due to adhesion or contact integrity failures; and (3) limited availability of cost‐effective processes and equipment for metal plating. For integrated circuits, Cu's low electrical resistance and high resistance to electromigration provided an impetus for the large investment in process development that was required to realise Cu‐plated interconnects. However, the technical advantages of using Cu for Si solar cell contacts are not as compelling, as solar cells can tolerate larger feature sizes thus reducing the criticality of the contact metal's conductivity and electromigration properties. Additionally, for Si photovoltaics, low cost is paramount, and new challenges arise from the need for modules to absorb light and operate in the field for 25+ years in diverse outdoor climates. However, with the scale of Si photovoltaic manufacturing expected to increase dramatically in the next decade, the use of large quantities of silver for cell metallisation will provide an incentive to address reliability concerns regarding the use of Cu for Si photovoltaic metallisation.

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Fundamentals of ultrafast laser–material interaction

Abstract: Abstract

Cited by 214 publications

References 63 publications

Phonon-induced long-lasting nonequilibrium in the electron system of a laser-excited solid

Phonon-induced long-lasting nonequilibrium in the electron system of a laser-excited solid

Pulsed‐Laser‐Induced IR Stereoscopic Imaging

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

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