Laser-Processing for Patterned and Free-Standing Nitride Films

1997 ◽  
Vol 482 ◽  
Author(s):  
M. K. Kelly ◽  
O. Ambacher ◽  
R. Dimitrov ◽  
H. Angerer ◽  
R. Handschuh ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Laser Processing ◽  
Elevated Temperatures ◽  
Pulsed Laser ◽  
Nitride Semiconductors ◽  
Free Standing ◽  
Nitrogen Gas ◽  
Buried Interfaces ◽  
Growth Substrates

AbstractFilms of GaN and related materials can be processed by methods that invoke thermal decomposition, induced by intense illumination with a pulsed laser. At elevated temperatures, the nitride semiconductors undergo decomposition, with the effusion of nitrogen gas. We exploit this mechanism as an alternative to etching for the patterning of nitride films and for the opening of buried interfaces. Films of GaN have been etched to a depth of 1 μm in less than three seconds. This interface decomposition allows in particular the separation of nitride films from transparent growth substrates such as sapphire.

Structural and Magneto-Electric Properties of Pulsed Laser Deposited Ferroelectric/Ferromagnetic Heterostructure

2009 ◽  
Vol 1199 ◽  
Author(s):  
Ricardo Martinez ◽  
Ashok Kumar ◽  
Ratnakar Palai ◽  
Ram S. Katiyar
Keyword(s):  
Elevated Temperatures ◽  
High Strain ◽  
Ferroelectric Properties ◽  
Pulsed Laser ◽  
Ferromagnetic Behavior ◽  
Asymmetric Behavior ◽  
Normal Behavior ◽  
Wide Range ◽  
Capacitance Voltage ◽  
Voltage Relationship

AbstractAsymmetric superlattices (SLs) with ferromagnetic La0.7Sr0.3MnO3 (LSMO) and ferroelectric Ba0.7Sr0.3TiO3 (BST) as constitutive layers were fabricated on conducting LaNiO3 (LNO) coated (001) oriented MgO substrates using pulsed laser deposition (PLD). The crystallinity, ferroelectric and magnetic properties of the SLs were studied over a wide range of temperatures and frequencies. The structure exhibited ferromagnetic behavior at 300K, and ferroelectric behavior over a range of temperatures between 100K and 300K. The dielectric response as a function of frequency obeys normal behavior below 300 K, whereas it follows Maxwell–Wagner model at elevated temperatures. The effect of ferromagnetic LSMO layers on ferroelectric properties of the SL indicated strong influence of the interfaces. The asymmetric behavior of ferroelectric loop and the capacitance-voltage relationship suggest development of a built field in the SLs due to high strain across the interfaces.

The effect of subsequent laser processing on the properties of welded joints made by pulsed laser welding

2021 ◽  
pp. 1-7
Author(s):  
A. V. Bogdanov ◽  
B. V. Buketkin ◽  
A. A. Kholopov ◽  
A. V. Perestoronin ◽  
R. Galiullin
Keyword(s):  
Laser Welding ◽  
Welded Joints ◽  
Laser Processing ◽  
Pulsed Laser ◽  
Pulsed Laser Welding

Two- and Three-Dimensional Photonic Crystals Produced by Pulsed Laser Irradiation in Silver-Doped Glass

2004 ◽  
Vol 99-100 ◽  
pp. 65-72
Author(s):  
Yuri S. Kaganovsky ◽  
I. Antonov ◽  
M. Rosenbluh ◽  
J. Ihlemann ◽  
A.A. Lipovskii
Keyword(s):  
Photonic Crystals ◽  
Laser Irradiation ◽  
Uv Irradiation ◽  
Elevated Temperatures ◽  
Pulsed Laser ◽  
Silver Nanoclusters ◽  
Direct Laser ◽  
Doped Glass ◽  
2D And 3D ◽  
Pulsed Laser Irradiation

Two types of silver-doped glass were used for direct laser recording of 2D and 3D photonic crystals. The first contained a diffusion layer (20 microns thick) with embedded silver nanoclusters of 20-nm average radius. 2D and 3D photonic crystals of submicron lattice parameters were fabricated by nanosecond pulsed laser irradiation (l, = 355 nm) using four or five coherent intersecting beams. Under irradiation the clusters absorbing light energy are heated to high temperatures and become mobile due to the formation of liquid shells around them. Adjacent clusters move towards each other and towards the irradiated surface under local temperature gradients, form agglomerates and merge in periodically located "spots" of high light intensity in the interference field. The second type of glass, photosensitive to UV irradiation, contained in the bulk Ag+ and Ce3+ ions. Under UV irradiation excited electrons passed from Ce3+ to Ag+. The Ag atoms became neutral and under subsequent heat treatment of the glass at elevated temperatures have a tendency to form nanoclusters, thus “developing” the UV recorded patterns. Using nanosecond pulsed irradiation of 308 nm we have recorded 3D photonic crystals in the bulk of such glass.

scholarly journals The effect of cobalt on morphology, structure, and ORR activity of electrospun carbon fibre mats in aqueous alkaline environments

2021 ◽  
Vol 12 ◽  
pp. 1173-1186
Author(s):  
Markus Gehring ◽  
Tobias Kutsch ◽  
Osmane Camara ◽  
Alexandre Merlen ◽  
Hermann Tempel ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Elevated Temperatures ◽  
Current Collector ◽  
Alkaline Media ◽  
Emission Spectrometry ◽  
Free Standing ◽  
X Ray ◽  
Turbostratic Carbon ◽  
Current Densities

An innovative approach for the design of air electrodes for metal–air batteries are free-standing scaffolds made of electrospun polyacrylonitrile fibres. In this study, cobalt-decorated fibres are prepared, and the influence of carbonisation temperature on the resulting particle decoration, as well as on fibre structure and morphology is discussed. Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, and inductively coupled plasma optical emission spectrometry are used for characterisation. The modified fibre system is compared to a benchmark system without cobalt additives. Cobalt is known to catalyse the formation of graphite in carbonaceous materials at elevated temperatures. As a result of cobalt migration in the material the resulting overall morphology is that of turbostratic carbon. Nitrogen removal and nitrogen-type distribution are enhanced by the cobalt additives. At lower carbonisation temperatures cobalt is distributed over the surface of the fibres, whereas at high carbonisation temperatures it forms particles with diameters up to 300 nm. Free-standing, current-collector-free electrodes assembled from carbonised cobalt-decorated fibre mats display promising performance for the oxygen reduction reaction in aqueous alkaline media. High current densities at an overpotential of 100 mV and low overpotentials at current densities of 333 μA·cm−2 were found for all electrodes made from cobalt-decorated fibre mats carbonised at temperatures between 800 and 1000 °C.

Pulsed Excimer Laser Processing of AlN/GaN Thin Films

1996 ◽  
Vol 449 ◽  
Author(s):  
W. S. Wong ◽  
L. F. Schloss ◽  
G.S. Sudhir ◽  
B. P. Linder ◽  
K-M. Yu ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Density ◽  
Excimer Laser ◽  
Laser Processing ◽  
Laser Annealing ◽  
Rutherford Backscattering Spectrometry ◽  
Pulsed Laser ◽  
Emission Peak ◽  
Dopant Activation ◽  
Pulsed Laser Annealing

ABSTRACTA KrF (248 nm) excimer laser with a 38 ns pulse width was used to study pulsed laser annealing of AIN/GaN bi-layers and dopant activation of Mg-implanted GaN thin films. For the AIN/GaN bi-layers, cathodoluminescence (CL) showed an increase in the intensity of the GaN band-edge peak at 3.47 eV after pulsed laser annealing at an energy density of 2000 mJ/cm2. Rutherford backscattering spectrometry of a Mg-implanted A1N (75 nm thick)/GaN (1.0 μm thick) thin-film heterostructure showed a 20% reduction of the 4He+ backscattering yield after laser annealing at an energy density of 400 mJ/cm2. CL measurements revealed a 410 nm emission peak indicating the incorporation of Mg after laser processing.

Sign in / Sign up

Export Citation Format

Share Document