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.

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.

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.

Selective fabrication of Si nanodots and nanowires

MRS Advances ◽  
2016 ◽  
Vol 1 (33) ◽  
pp. 2337-2343
Author(s):  
Anahita Haghizadeh ◽  
Haeyeon Yang
Keyword(s):  
Atomic Force Microscopy ◽  
Laser Pulses ◽  
High Density ◽  
Single Application ◽  
Force Microscopy ◽  
Atomic Force ◽  
Large Density

ABSTRACTWe report observation of narrow nanowires and high density nanodots on the Si(001) surfaces when they are exposed to a single application of interferential irradiation of laser pulses of 7 ns. These nanostructures form selectively depending on interference parameters so that their placements can be controlled by controlling the parameters. The morphologies of the nanostructures are studied by atomic force microscopy. The nanowire width increases with interference period. The narrowest nanowires observed have the width smaller than 26 nm, which is eight times smaller than the interference period while the nanodots have a very large density of 1.8 ± 0.45) × 1011/cm2.

Ball-Milling Graphite Used for Synthesis of Biocompatible Blue Luminescent Graphene Quantum Dots

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Zhou J ◽  
◽  
Dong Y ◽  
Ma Y ◽  
Zhang T ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ball Milling ◽  
Graphene Quantum Dots ◽  
Raw Material ◽  
Hydroxyl Groups ◽  
High Quality ◽  
Widespread Application ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Graphene Quantum Dots (GQDs) have been prepared by oxidationhydrothermal reaction, using ball-milling graphite as the starting materials. The prepared GQDs are endowed with excellent luminescence properties, with the optimum emission of 320nm. Blue photoluminescent emitted from the GQDs under ultraviolet light. The GQDs are ~3nm in width and 0.5~2 nm in thickness, revealed by high-resolution transmission electron microscopy and atomic force microscopy. In addition, Fourier transform infrared spectrum evidences the existence of carbonyl and hydroxyl groups, meaning GQDs can be dispersed in water easily and used in cellar imaging, and blue area inside L929 cells were clearly observed under the fluorescence microscope. Both low price of raw material and simple prepared method contribute to the high quality GQDs widespread application in future.

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.

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