Realization of ∼10 nm Features on Semiconductor Surfaces via Femtosecond Laser Direct Patterning in Far Field and in Ambient Air

As a noncontact strategy with flexible tools and high efficiency, laser precision engineering is a significant advanced processing way for high-quality micro-/nanostructure fabrication, especially to achieve novel functional photoelectric structures and devices. For the microscale creation, several femtosecond laser fabrication methods, including multiphoton absorption, laser-induced plasma-assisted ablation, and incubation effect have been developed. Meanwhile, the femtosecond laser can be combined with microlens arrays and interference lithography techniques to achieve the structures in submicron scales. Down to nanoscale feature sizes, advanced processing strategies, such as near-field scanning optical microscope, atomic force microscope, and microsphere, are applied in femtosecond laser processing and the minimum nanostructure creation has been pushed down to ~25 nm due to near-field effect. The most fascinating femtosecond laser precision engineering is the possibility of large-area, high-throughput, and far-field nanofabrication. In combination with special strategies, including dual femtosecond laser beam irradiation, ~15 nm nanostructuring can be achieved directly on silicon surfaces in far field and in ambient air. The challenges and perspectives in the femtosecond laser precision engineering are also discussed.

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Study of the formation of 3-D titania nanofibrous structure by MHz femtosecond laser in ambient air

10.32920/14639553 ◽

2021 ◽

Author(s):

Amirhossein Tavangar ◽

Bo Tan ◽

Krishnan Venkatakrishnan

Keyword(s):

Laser Ablation ◽

Femtosecond Laser ◽

Deposition Rate ◽

Femtosecond Laser Ablation ◽

Ambient Air ◽

Experimental Results ◽

Laser Parameters ◽

Nanofibrous Structure ◽

Titania Nanostructures ◽

Multiple Pulses

In this study, we describe the formation mechanism of web-like three-dimensional (3-D) titania nanofibrous structures during femtosecond laser ablation of titanium (Ti) targets in the presence of background air. First, we demonstrate the mechanism of ablation of Ti targets by multiple femtosecond laser pulses at ambient air in an explicit analytical form. The formulas for evaporation rates and the number of ablated particles, which is analogous to the deposition rate of the synthesized nanofibers, for the ablation by a single pulse and multiple pulses as a function of laser parameters, background gas, and material properties are predicted and compared to experimental results. Afterwards, the formation of nanofibrous structures is demonstrated by applying an existing simplified kinetic model to Ti targets and ambient conditions. The predicted theory provides nanofiber diameter dependency with the combination of laser parameters, target properties, and ambient gas characteristics. Experimental studies are then performed on titania nanofibrous structures synthesized by laser ablation of Ti targets using MHz repletion-rate femtosecond laser at ambient air. The models' predictions are then compared with the experimental results, where nanostructures with different morphologies are manufactured by altering laser parameters. Our results indicate that femtosecond laser ablation of Ti targets at air background yields crystalline titania nanostructures. The formation of crystalline titania nanostructures is preceded b thermal mechanism of nucleation and growth. The results point out that laser pulse repetition and dwell time can control the density, size, and pore size of the engineered nanofibrous structure. As the deposition rate of nanostructures is analogous to the ablation rate of the target, higher density of nanofibrous structure is seen at greater laser fluences. The predicted theory can be applied to predict ablation mechanism and nanofiber formation of different materials.

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Study of ambient air ionization with femtosecond laser pulses

10.1117/12.575635 ◽

2005 ◽

Cited By ~ 2

Author(s):

Yi Wang ◽

Xiaolei Wang ◽

Nan Zhang ◽

Hongchen Zhai ◽

Xiaonong Zhu

Keyword(s):

Femtosecond Laser ◽

Laser Pulses ◽

Ambient Air ◽

Femtosecond Laser Pulses ◽

Air Ionization

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Effects of Ambient Air Pressure on Femtosecond Laser Induced Periodic Ripple Structure on Chromium Films

ACTA PHOTONICA SINICA ◽

10.3788/gzxb20184707.0714001 ◽

2018 ◽

Vol 47 (7) ◽

pp. 714001

Author(s):

刘琦 LIU Qi ◽

张楠 ZHANG Nan ◽

杨建军 YANG Jian-jun

Keyword(s):

Femtosecond Laser ◽

Ambient Air ◽

Air Pressure ◽

Ripple Structure ◽

Chromium Films

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Simplified formulas for the generation of terahertz waves from semiconductor surfaces excited with a femtosecond laser

Journal of Applied Physics ◽

10.1063/5.0005623 ◽

2020 ◽

Vol 127 (24) ◽

pp. 245703 ◽

Cited By ~ 3

Author(s):

Masayoshi Tonouchi

Keyword(s):

Femtosecond Laser ◽

Semiconductor Surfaces ◽

Terahertz Waves

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Direct Writing of Copper Micropatterns Using Near-Infrared Femtosecond Laser-Pulse-Induced Reduction of Glyoxylic Acid Copper Complex

Micromachines ◽

10.3390/mi10060401 ◽

2019 ◽

Vol 10 (6) ◽

pp. 401 ◽

Cited By ~ 3

Author(s):

Mizue Mizoshiri ◽

Keiko Aoyama ◽

Akira Uetsuki ◽

Tomoji Ohishi

Keyword(s):

Laser Pulse ◽

Femtosecond Laser ◽

Line Width ◽

Co2 Laser ◽

Near Infrared ◽

Glyoxylic Acid ◽

Ambient Air ◽

Femtosecond Laser Pulses ◽

Direct Writing ◽

Cu Complex

We have fabricated Cu-based micropatterns in an ambient environment using femtosecond laser direct writing to reduce a glyoxylic acid Cu complex spin-coated onto a glass substrate. To do this, we scanned a train of focused femtosecond laser pulses over the complex film in air, following which the non-irradiated complex was removed by rinsing the substrates with ethanol. A minimum line width of 6.1 µm was obtained at a laser-pulse energy of 0.156 nJ and scanning speeds of 500 and 1000 µm/s. This line width is significantly smaller than that obtained in previous work using a CO2 laser. In addition, the lines are electrically conducting. However, the minimum resistivity of the line pattern was 2.43 × 10−6 Ω·m, which is ~10 times greater than that of the pattern formed using the CO2 laser. An X-ray diffraction analysis suggests that the balance between reduction and re-oxidation of the glyoxylic acid Cu complex determines the nature of the highly reduced Cu patterns in the ambient air.

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