Direct laser patterning of GaAs(001) surfaces

2014 ◽  
Vol 1628 ◽  
Author(s):  
Haeyeon Yang
Keyword(s):  
Laser Intensity ◽  
Laser Pulses ◽  
Patterned Surfaces ◽  
Power Laser ◽  
Force Microscopy ◽  
Patterned Surface ◽  
Laser Patterning ◽  
Atomic Force ◽  
Plateau Area ◽  
Direct Laser

ABSTRACTAnalysis of surface images indicates that GaAs(001) surfaces can be patterned directly by applying interferential irradiation of high power laser pulses on the surface. Atomic force microscopy (AFM) was used to image the patterned surfaces. The patterned surface shows strips that have the same separation as the interference period used. The direct laser patterning leaves the surface with trenches. The depth of trenches increases with the laser intensity and can be varied from few nanometers to a few hundred nanometers. At low laser intensity, strip shaped mound appears at the both edges of a trench, leaving a plateau area between them. The width of mound increases with the laser intensity, making the plateau area smaller. With a higher laser intensity, the plateau area disappear as the mounds merge together, forming a single strip between the adjacent trenches. AFM images from the patterned surface indicate that direct laser patterning can be used to fabricate nanostructures with a period smaller than that of the interference period as well as the wavelength of the laser used.

Direct laser fabrication of nanostructures on Si(001)

2015 ◽  
Vol 1748 ◽  
Author(s):  
Anahita Haghizadeh ◽  
Haeyeon Yang
Keyword(s):  
Laser Pulses ◽  
Surface Strain ◽  
Power Laser ◽  
Laser Fabrication ◽  
Force Microscopy ◽  
Atomic Force ◽  
Direct Laser ◽  
Direct Laser Fabrication ◽  
Transient Thermal ◽  
Base Width

ABSTRACTWe study how the period of transient thermal gradient impacts on morphologies of nanostructures on the Si(001) surface. Strain-free, self-assembled nanodots as well as periodic nanowires are fabricated directly on Si(001) surfaces by applying high power laser pulses on the surface interferentially. The morphologies of the nanostructures are studied by atomic force microscopy. Generally, the laser irradiated surfaces show nanowires but nanodots are also observed. The nanowire width increases with interference period. The narrowest nanowires observed have the width smaller than 50 nm, which is four times smaller than the interference period while the nanodots have a base width of 43 nm and height of 8 nm.

High density quantum dots by direct laser fabrication

MRS Advances ◽  
2016 ◽  
Vol 1 (28) ◽  
pp. 2025-2030 ◽  
Author(s):  
Anahita Haghizadeh ◽  
Haeyeon Yang
Keyword(s):  
Quantum Dots ◽  
Critical Density ◽  
Laser Pulses ◽  
High Density ◽  
Power Laser ◽  
Laser Fabrication ◽  
Force Microscopy ◽  
Atomic Force ◽  
Direct Laser ◽  
Direct Laser Fabrication

ABSTRACTWe report a study of direct laser fabrication that produces quantum dots with their density higher than the critical density without appearance of large clumps. Atomic force microscopy is used to image GaAs(001) surfaces that are irradiated by high power laser pulses interferentially. The analysis suggests that high density quantum dots be fabricated directly on semiconductor surfaces during epitaxial growth processes.

scholarly journals Two-Photon Polymerization of Albumin Hydrogel Nanowires Strengthened with Graphene Oxide

Biomimetics ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 66
Author(s):  
Nikita Nekrasov ◽  
Natalya Yakunina ◽  
Vladimir Nevolin ◽  
Ivan Bobrinetskiy ◽  
Pavel Vasilevsky ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Nanoelectromechanical Systems ◽  
Force Microscopy ◽  
Two Photon ◽  
Direct Laser ◽  
Two Photon Polymerization

Multifunctional biomaterials can pave a way to novel types of micro- and nanoelectromechanical systems providing benefits in mimicking of biological functions in implantable, wearable structures. The production of biocomposites that hold both superior electrical and mechanical properties is still a challenging task. In this study, we aim to fabricate 3D printed hydrogel from a biocomposite of bovine serum albumin with graphene oxide (BSA@GO) using femtosecond laser processing. We have developed the method for functional BSA@GO composite nanostructuring based on both two-photon polymerization of nanofilaments and direct laser writing. The atomic-force microscopy was used to probe local electrical and mechanical properties of hydrogel BSA@GO nanowires. The improved local mechanical properties demonstrate synergistic effect in interaction of femtosecond laser pulses and novel composite structure.

scholarly journals LIPSS Structures Induced on Graphene-Polystyrene Composite

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3460 ◽  
Author(s):  
Dominik Fajstavr ◽  
Klára Neznalová ◽  
Václav Švorčík ◽  
Petr Slepička
Keyword(s):  
Chemical Properties ◽  
Laser Pulses ◽  
Periodic Pattern ◽  
Krypton Fluoride ◽  
Periodic Surface ◽  
Laser Modification ◽  
Force Microscopy ◽  
Periodic Surface Structure ◽  
Atomic Force ◽  
Physico Chemical

A laser induced periodic surface structure (LIPSS) on graphene doped polystyrene was prepared by the means of a krypton fluoride (KrF) laser with the wavelength of 248 nm and precisely desired physico-chemical properties were obtained for the structure. Surface morphology after laser modification of polystyrene (PS) doped with graphene nanoplatelets (GNP) was studied. Laser fluence values of modifying laser light varied between 0–40 mJ·cm−2 and were used on polymeric PS substrates doped with 10, 20, 30, and 40 wt. % of GNP. GNP were incorporated into PS substrate with the solvent casting method and further laser modification was achieved with the same amount of laser pulses of 6000. Formed nanostructures with a periodic pattern were examined by atomic force microscopy (AFM). The morphology was also studied with scanning electron microscopy SEM. Laser irradiation resulted in changes of chemical composition on the PS surface, such as growth of oxygen concentration. This was confirmed with energy-dispersive X-ray spectroscopy (EDS).

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.

scholarly journals Дифракционные решетки с блеском, получаемые на пластинах Si --- первые результаты

2021 ◽  
Vol 91 (10) ◽  
pp. 1538
Author(s):  
Л.И. Горай ◽  
Т.Н. Березовская ◽  
Д.В. Мохов ◽  
В.А. Шаров ◽  
К.Ю. Шубина ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Root Mean Square Roughness ◽  
Force Microscopy ◽  
Laser Lithography ◽  
Atomic Force ◽  
Groove Profile ◽  
Direct Laser ◽  
Triangular Profile ◽  
Extreme Ultraviolet Radiation ◽  
Protective Mask

Using direct laser lithography and liquid etching of polished vicinal Si(111) wafers, a technology was developed and diffraction gratings 500 /mm with a blaze angle of 4° were fabricated. The manufacturing process of a reflective Si-grating of a triangular profile (sawtooth) can be divided into four main steps: (1) obtaining a pattern of a protective mask for etching grooves; (2) anisotropic etching of grooves in KOH solution; (3) etching to smooth the grating profile and polish the surface of working facets; (4) coating to increase reflectivity. The samples obtained were characterized using scanning electron microscopy and atomic force microscopy methods to determine the shape of the groove profile and roughness: the shape turned out to be close to the ideal triangular, and the root-mean square roughness was less than 0.3 nm. With the help of the PCGrate™ code, taking into account the measured real groove profile, the diffraction efficiency of gratings operating in classical and conical mounts in soft-X-ray and extreme ultraviolet radiation has been simulated. The obtained efficiency values are close to the record ones for the corresponding spectral range and the Au-coating of the grating.

scholarly journals Photoelectrical properties investigated on individual Si nanowires and their size dependence

2020 ◽  
Author(s):  
Xiaofeng Hu ◽  
Shujie Li ◽  
Zuimin Jiang ◽  
Xinju Yang
Keyword(s):  
Barrier Height ◽  
Size Dependence ◽  
Laser Intensity ◽  
Electrostatic Force ◽  
Si Nanowires ◽  
Practical Applications ◽  
Force Microscopy ◽  
Photoelectrical Properties ◽  
Atomic Force ◽  
Different Diameters

Abstract Periodically ordered arrays of vertically aligned Si nanowires (Si NWs) are successfully fabricated with controllable diameters and lengths. Their photoconductive properties are investigated by photoconductive atomic force microscopy (PCAFM) on individual nanowires. The results show that the photocurrent of Si NWs increases significantly with the laser intensity, indicating that Si NWs have good photoconductance and photoresponse capability. This photo-enhanced conductance can be attributed to the photo-induced Schottky barrier change, confirmed by I-V curve analyses. On the other hand, electrostatic force microscopy (EFM) results indicate that a large number of photo-generated charges are trapped in Si NWs under laser irradiation, leading to the lowering of barrier height. Moreover, the size dependence of photoconductive properties is studied on Si NWs with different diameters and lengths. It is found that the increasing magnitude of photocurrent with laser intensity is greatly relevant to the nanowires’ diameter and length. Si NWs with smaller diameters and shorter lengths display better photoconductive properties, which agrees well with the size-dependent barrier height variation induced by photo-generated charges. With optimized diameter and length, great photoelectrical properties are achieved on Si NWs. Overall, in this study the photoelectrical properties of individual Si NWs are systematically investigated by PCAFM and EFM, providing important information for the optimization of nanostructures for practical applications.

CVD Growth and Excimer Laser Processing of SiGe Alloys Monitored by Single Wavelength Ellipsometry and Atomic Force Microscopy

1997 ◽  
Vol 502 ◽  
Author(s):  
R. Larciprete ◽  
G. Padeletti ◽  
S. Cozzi ◽  
S. Pieretti
Keyword(s):  
Atomic Force Microscopy ◽  
Laser Processing ◽  
Growth Parameters ◽  
Laser Pulses ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Analysis ◽  
Cvd Growth ◽  
Sample Irradiation

ABSTRACTSingle wavelength ellipsometry was used to monitor the CVD growth of Si(1-x)Gex alloys onSi and to evaluate the effect of sample irradiation by KrF laser pulses, performed during or afterthe CVD growth. The information obtained was correlated with AFM analysis results in order tooptimize the growth parameters for an improved morphological quality of the alloy layers.

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.

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