Structural changes in GaAs induced by ultrafast (fs) laser pulses

1998 ◽  
Vol 13 (7) ◽  
pp. 1808-1811 ◽  
Author(s):  
L. Nánai ◽  
R. Vajtai ◽  
Cs. Beleznai ◽  
J. Remes ◽  
S. Leppävuori ◽  
...  
Keyword(s):  
Structural Changes ◽  
Microprobe Analysis ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Electron Hole ◽  
Zinc Blend ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Hole Plasma ◽  
Fs Laser

Ultrafast changes in the crystal structure of GaAs induced by intense femtosecond laser pulses are detected and investigated. Atomic force microscopy and Raman microprobe analysis of the laser-treated area show centrosymmetric (disordered) features which are different from the original zinc-blend structure of the GaAs lattice. The frozen-in structure shows evidence for a special heat transfer from the laser-induced crater to the boundary, namely the heat has been transferred ballistically by a high-density electron-hole plasma.

Femtosecond Laser Micromachining of Periodical Structures in Si

2004 ◽  
Vol 850 ◽  
Author(s):  
Mohamed El-Bandrawy ◽  
Mool C. Gupta
Keyword(s):  
Laser Pulses ◽  
Light Polarization ◽  
Objective Lens ◽  
Force Microscopy ◽  
Laser Parameters ◽  
Femtosecond Laser Micromachining ◽  
Atomic Force ◽  
Fs Laser ◽  
Polarization Orientation

ABSTRACTA frequency doubled femtosecond Ti: sapphire laser at a wavelength of 400 nm, a pulse width of 160 fs, and a repetition rate of 1 kHz was used with a computer controlled galvo head to write periodical structures in Si <100>. Laser pulses of ∼130 nJ were focused using an objective lens of 0.65 NA. Laser parameters were optimized for efficient submicron ablation, yielding 700 nm wide by 600 nm deep lines. 1-D and 2-D periodical structures of 5 and 5x5 micron periods, respectively, were fabricated and examined using optical and atomic force microscopy. The quality of the 1-D and 2-D structures was highly depended on the light polarization orientation with respect to micromachining direction. With optimized fs laser parameters, high quality 1-D and 2-D periodical structures were obtained, which would have applications in optical devices.

Ultrafast Laser Induced Structural Modification of Fused Silica—Part I: Feature Formation Mechanisms

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Siniša Vukelić ◽  
Panjawat Kongsuwan ◽  
Y. Lawrence Yao
Keyword(s):  
Femtosecond Laser ◽  
Material Properties ◽  
Structural Changes ◽  
Three Dimensional ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Optical Data ◽  
Formation Mechanisms ◽  
Force Microscopy

Nonlinear absorption of femtosecond-laser pulses enables the induction of structural changes in the interior of bulk transparent materials without affecting their surface. This property can be exploited for transmission welding of transparent dielectrics, three dimensional optical data storages, and waveguides. In the present study, femtosecond-laser pulses were tightly focused within the interior of bulk fused silica specimen. Localized plasma was formed, initiating rearrangement of the network structure. Features were generated through employment of single pulses as well as pulse trains using various processing conditions. The change in material properties were studied through employment of differential interference contrast optical microscopy and atomic force microscopy. The morphology of the altered material as well as the nature of the physical mechanisms (thermal, explosive plasma expansion, or in-between) responsible for the alteration of material properties as a function of process parameters is discussed.

Recombination of an electron-hole plasma in silicon under the action of femtosecond laser pulses

JETP Letters ◽  
2004 ◽  
Vol 79 (11) ◽  
pp. 529-531 ◽  
Author(s):  
S. I. Ashitkov ◽  
A. V. Ovchinnikov ◽  
M. B. Agranat
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Electron Hole ◽  
Hole Plasma ◽  
Electron Hole Plasma

Microstructures induced by femtosecond laser pulses inside glasses

2009 ◽  
Vol 24 (6) ◽  
pp. 1983-1988 ◽  
Author(s):  
Dong Su ◽  
Nan Jiang ◽  
Jianrong Qiu ◽  
John C.H. Spence
Keyword(s):  
Structural Changes ◽  
Soda Lime ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Transmission Electron ◽  
Fs Laser ◽  
Soda Lime Silicate Glass ◽  
Spectroscopy Studies ◽  
Property Changes ◽  
Electron Energy Loss

In this article, the chemical and structural changes inside soda-lime glasses induced by femtosecond (fs) laser pulsing have been reported, based on transmission electron microscopy and electron energy loss spectroscopy studies. Under fs-laser interaction, Na-rich phases are formed, and Na nanoparticles are also precipitated around the Na-rich phases. These findings demonstrate how powerful and efficient the fs-laser pulsing and interaction can be in making novel microstructures in soda-lime silicate glass, and they bridge the gap between the macroscale property changes and nanometer-scale structures.

Nanofluidic capillaries produced via femtosecond laser induced delamination of thin thermal oxide films from Si(100) substrates

2005 ◽  
Vol 901 ◽  
Author(s):  
Joel Patrick McDonald ◽  
Vanita R. Mistry ◽  
Katherine E. Ray ◽  
Steven M. Yalisove
Keyword(s):  
Femtosecond Laser ◽  
Oxide Films ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Force Microscopy ◽  
Automated Translation ◽  
Atomic Force ◽  
Integrated Devices ◽  
Thermal Oxide ◽  
Translation Stage

AbstractHighly selective and repeatable delamination of thermal oxide films from Si(100) substrates has been performed using single and multiple femtosecond laser pulses forming bubbles or blisters. By overlapping the bubbles laterally, tubes or capillaries can be formed with a range of volumes suitable for nanofluidics. By scanning the sample through the laser using an automated translation stage, patterns of tubes with arbitrary complexity can be formed, while the scan velocity can easily control the volume of the tubes. The production time for capillaries in this fashion is considerably less than with other lithographic techniques, while the proximity of the tubes to the underlying silicon substrate yields the possibility for integrated devices. The mechanism responsible for the delamination will be discussed and the optimal laser and sample translation conditions will be presented which provide the most uniform tubes. Atomic force microscopy and optical microscopy of capillaries with a range of volumes will be presented.

Crystallization of Optically Thick Amorphous Silicon Films by Near-IR Femtosecond Laser Processing

2020 ◽  
Vol 312 ◽  
pp. 134-139
Author(s):  
Eugeny Mitsai ◽  
Alexander V. Dostovalov ◽  
Kirill A. Bronnikov ◽  
Aleksandr Vladimirovich Nepomniaschiy ◽  
Aleksey Y. Zhizhchenko ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Annealed Film ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Force Microscopy ◽  
Near Ir ◽  
Atomic Force ◽  
Femtosecond Laser Processing ◽  
Amorphous Si ◽  
Si Films

We demonstrated efficient crystallization of amorphous Si films induced by their direct irradiation with near-IR femtosecond laser pulses coming at sub-MHz repetition rate. Comprehensive analysis of morphology and composition of the laser-annealed film by atomic-force microscopy, Fourier-transform IR, Raman and energy dispersive X-ray spectroscopy as well as numerical modeling of optical spectra confirmed efficient crystallization of amorphous Si and high-quality of the obtained films opening pathway for applications in thin-film solar cells, transistors and displays.

Determination of the Physical Properties of Oil Sands Components using Scanning Probe Microscopy

2015 ◽  
Vol 1754 ◽  
pp. 69-74
Author(s):  
Ravi Gaikwad ◽  
Tinu Abraham ◽  
Aharnish Hande ◽  
Fatemeh Bakhtiari ◽  
Siddhartha Das ◽  
...  
Keyword(s):  
Oil Sands ◽  
Structural Changes ◽  
Rational Approach ◽  
Kelvin Probe ◽  
Scanning Calorimetry ◽  
Probe Microscopy ◽  
Kelvin Probe Microscopy ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTAtomic force microscopy is employed to study the structural changes in the morphology and physical characteristics of asphaltene aggregates as a function of temperature. The exotic fractal structure obtained by evaporation-driven asphaltene aggregates shows an interesting dynamics for a large range of temperatures from 25°C to 80°C. The changes in the topography, surface potential and adhesion are unnoticeable until 70°C. However, a significant change in the dynamics and material properties is displayed in the range of 70°C - 80°C, during which the aspahltene aggregates acquire ‘liquid-like’ mobility and fuse together. This behaviour is attributed to the transition from the pure amorphous phase to a crystalline liquid phase which occurs at approximately 70°C as shown by using Differential Scanning Calorimetry (DSC). Additionally, the charged nature of asphaltenes and bitumen is also explored using kelvin probe microscopy. Such observations can lead to the development of a rational approach to the fundamental understanding of asphaltene aggregation dynamics and may help in devising novel techniques for the handling and separation of asphaltene aggregates using dielectrophoretic methods.

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