scholarly journals Воздействие импульсов эксимерного лазера на светоизлучающие InGaAs/GaAs-структуры с (Ga, Mn)As-слоем

2021 ◽  
Vol 63 (3) ◽  
pp. 346
Author(s):  
О.В. Вихрова ◽  
Ю.А. Данилов ◽  
Б.Н. Звонков ◽  
И.Л. Калентьева ◽  
Ю.М. Кузнецов ◽  
...  
Keyword(s):  
Energy Density ◽  
Quantum Well ◽  
Quantum Wells ◽  
Laser Annealing ◽  
Laser Energy ◽  
Laser Action ◽  
Pulsed Laser ◽  
Indium Content ◽  
Heat Propagation ◽  
Radiative Properties

It was studied the possibility of laser annealing modification of the properties of the (Ga,Mn)As layer located on the surface of a quantum-well InGaAs/GaAs structure, while retaining its radiative properties. The structures with four InGaAs/GaAs quantum wells (indium content was varied from 0.08 to 0.25), located at different distances from the (Ga,Mn)As layer, were fabricated by combining the methods of MOCVD-hydride epitaxy and pulsed laser deposition. The LPX-200 excimer laser pulse energy density was varied from 200 to 360 mJ/cm2, and the depth of laser action was determined from the change in the photoluminescence spectra of the quantum wells. In describing the results obtained, a model of the laser annealing process was used, based on solving the problem of heat propagation in a one-dimensional GaAs system, taking into account the (Ga,Mn)As layer on the surface. Changes in the structural and galvanomagnetic properties of the samples as a result of laser irradiation were analyzed. It is shown that as a result of pulsed laser action at a laser energy density range of 250 - 300 mJ/cm2, it is possible to preserve the emissive properties of the active region (InGaAs/GaAs quantum well) located at a distance of 10 - 12 nm from the (Ga,Mn)As layer and modify ferromagnetic properties of the semiconductor (Ga,Mn)As, namely: to increase the temperature of the ferromagnet-paramagnetic phase transition to values of at least 120 K. The results obtained are promising for the development of technology for devices of spin optoelectronics.

Formation of Q-carbon by adjusting sp3 content in diamond-like carbon films and laser energy density of pulsed laser annealing

Carbon ◽  
2020 ◽  
Vol 167 ◽  
pp. 504-511 ◽  
Author(s):  
Hiroki Yoshinaka ◽  
Seiko Inubushi ◽  
Takanori Wakita ◽  
Takayoshi Yokoya ◽  
Yuji Muraoka
Keyword(s):  
Energy Density ◽  
Laser Annealing ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Carbon Films ◽  
Laser Energy Density ◽  
Diamond Like Carbon ◽  
Pulsed Laser Annealing

Photoluminescence of Pulsed Ruby Laser Annealed Crystalline and Ion Implanted GaAs

1981 ◽  
Vol 4 ◽  
Author(s):  
Douglas H. Lowndes ◽  
Bernard J. Feldman
Keyword(s):  
Radiative Recombination ◽  
Laser Annealing ◽  
Laser Energy ◽  
Pulsed Laser ◽  
High Dose ◽  
Pulsed Laser Annealing ◽  
Recombination Centers ◽  
Pl Intensity ◽  
P Type ◽  
Ion Implanted

ABSTRACTIn an effort to understand the origin of defects earlier found to be present in p–n junctions formed by pulsed laser annealing (PLA) of ion implanted (II) semiconducting GaAs, photoluminescence (PL) studies have been carried out. PL spectra have been obtained at 4K, 77K and 300K, for both n–and p–type GaAs, for laser energy densities 0 ≤ El ≤ 0.6 J/cm2. It is found that PLA of crystalline (c−) GaAs alters the PL spectrum and decreases the PL intensity, corresponding to an increase in density of non-radiative recombination centers with increasing El. The variation of PL intensity with El is found to be different for n– and p–type material. No PL is observed from high dose (1 or 5×1015 ions/cm2 ) Sior Zn-implanted GaAs, either before or after laser annealing. The results suggest that the ion implantation step is primarily responsible for formation of defects associated with the loss of radiative recombination, with pulsed annealing contributing only secondarily.

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.

The Shallow Implantation of Bismuth During the Growth of Bismuth Nanocrystals in Al2O3 by Pulsed Laser Deposition

2003 ◽  
Vol 780 ◽  
Author(s):  
A. Suárez-García ◽  
J-P. Barnes ◽  
R. Serna ◽  
A. K. Petford-Long ◽  
C. N. Afonso ◽  
...  
Keyword(s):  
Energy Density ◽  
Cross Section ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Laser Energy Density ◽  
X Ray ◽  
Continuous Layer ◽  
Transmission Electron ◽  
Order Of Magnitude

AbstractThe effect of the laser energy density used to deposit Bi onto amorphous aluminum oxide (a-Al2O3) on the growth of Bi nanocrystals has been investigated using transmission electron microscopy of cross section samples. The laser energy density on the Bi target was varied by one order of magnitude (0.4 to 5 J cm-2). Across the range of energy densities, in addition to the Bi nanocrystals nucleated on the a-Al2O3 surface, a dark and apparently continuous layer appears below the nanocrystals. Energy dispersive X-ray analysis on the layer have shown it is Bi rich. The separation from the Bi layer to the bottom of the nanocrystals on top is consistent with the implantation range of Bi species in a-Al2O3. As the laser energy density increases, the implantation range has been measured to increase. The early stages of the Bi growth have been analyzed in order to determine how the Bi implanted layer develops.

Discharge-Pumped VUV F2 Molecular Laser Annealing of Heavily Se+-Implanted GaAs

1993 ◽  
Vol 316 ◽  
Author(s):  
Hajime Shibata ◽  
Yunosuke Makita ◽  
Kawakatsu Yamada ◽  
Yutaka Uchida ◽  
Sabro Satoh
Keyword(s):  
Energy Density ◽  
Raman Scattering ◽  
Laser Annealing ◽  
Laser Energy ◽  
Laser Energy Density ◽  
Furnace Annealing ◽  
Implantation Energy ◽  
Molecular Laser ◽  
First Time ◽  
Ion Implanted

ABSTRACTThe capability of discharge-pumped vacuum ultraviolet F2 molecular laser for laser annealing of heavily ion implanted semiconductor was demonstrated for the first time using Se+ heavily ion implanted GaAs. Cr-doped semi-insulationg GaAs wafers were used as the substrates, and the Se+ implantation energy and dose were controlled to 100 keV and 1× 1015 cm-2, respectively. Samples were annealed using a F2 molecular laser ( wavelength = 157 nm ) with a single pulse ( width ~ 20 ns ) in the energy density range from 200 to 800 mJ/cm2 in a nitrogen atmosphere. In addition, furnace annealing was done on separate samples at 850 ºC for 20 minutes in a purified hydrogen atmosphere for comparison. Characterization of the samples was carried out using Raman scattering and ellipsometry. The laser annealed samples exhibited intense Raman scattering LO phonon peaks whose intensity increased with increasing laser power density, whereas the furnace annealed samples exhibited a very weak LO phonon peak. It was demonstrated for the first time that VUV photons can be very effective in annealing ion implantation damage as compared with conventional furnace annealing. The behavior of Raman scattering spectra as a function of laser energy density was explained quantitatively by a “spatial correlation” model. The model made it possible to estimate the average size of the recovered crystal regions in samples for any given laser energy density.

Laser annealing of laser additive–manufactured Ni-Ti structures: An experimental–numerical investigation

2016 ◽  
Vol 232 (6) ◽  
pp. 1054-1067 ◽  
Author(s):  
S Shiva ◽  
IA Palani ◽  
CP Paul ◽  
B Singh
Keyword(s):  
Energy Density ◽  
Laser Annealing ◽  
Laser Energy ◽  
Experimental Studies ◽  
Mechanical Systems ◽  
Laser Energy Density ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Homogeneous Microstructure ◽  
Micro Electro Mechanical Systems

Tailored structures of Ni-Ti shape memory alloys for micro-electro-mechanical systems can be fabricated using laser additive manufacturing, and requisite homogeneous microstructure for predictive design and fabrication of micro-electro-mechanical systems devices can be achieved by annealing. Investigation has been performed on the laser annealing of laser additive–manufactured Ni-Ti structures using a pulsed green laser through numerical simulation and experimental studies. The parametric dependence showed that a laser energy density of 1100 mJ cm−2 has a considerable influence in annealing of Ni-Ti structures. The surface morphology, phase transformation temperature and microstructure of laser-annealed Ni-Ti structures were studied with scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. Laser energy density of 1100 mJ cm−2 was used for annealing the samples as identified in the simulation. Surface annealing of Ni-Ti led to a uniform surface of the material with an increase in grain size and surface roughness. A decrease in the micro-hardness of the samples was obtained as a result of laser annealing. Thus, the investigations demonstrated the improved properties of laser additive–manufactured Ni-Ti structures by laser annealing.

The effects of the atmosphere on the surface modification of alumina by pulsed-laser-irradiation

1997 ◽  
Vol 12 (7) ◽  
pp. 1747-1754 ◽  
Author(s):  
Siqi Cao ◽  
A. J. Pedraza ◽  
L. F. Allard ◽  
D. H. Lowndes
Keyword(s):  
Energy Density ◽  
Laser Pulse ◽  
Thin Layer ◽  
Amorphous Phase ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Near Surface ◽  
Metallic Particles ◽  
Cellular Microstructure

A near-surface thin layer is melted when alumina is pulsed-laser-irradiated in an Ar–4% H2 atmosphere or in air. A thin layer of amorphous phase forms when the substrates are irradiated in Ar–4% H2 at 1 to 1.3 J/cm2 with multiple laser pulses. Amorphous phase is also found in samples laser-irradiated in air and oxygen. After a laser pulse at an energy density of 1.6 J/cm2 or higher the melt solidifies epitaxially from the unmelted substrate with a cellular microstructure. There is a decrease in the cooling rate of the melt as the laser energy density is increased because more heat must be dissipated. The amorphous phase forms when the heat input due to the laser pulse produces a superheated melt that cools down sufficiently fast to avoid crystallization. Very small particles of aluminum in the laser-melted and subsequently solidified layer are observed only in samples laser-irradiated in an Ar–4% H2 atmosphere. In this reducing atmosphere, the alumina is possibly reduced to metallic aluminum which is mixed into the melt by the turbulence provoked by the laser pulses. The effects of these metallic particles on copper deposition when the irradiated substrates are immersed in an electroless bath are discussed.

Er-Doping in Silicon by Pulsed Laser Irradiation

1993 ◽  
Vol 301 ◽  
Author(s):  
Kenshiro Nakashima
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Energy Density ◽  
Er Doping ◽  
Erbium Ions ◽  
State Regime ◽  
Er Doped ◽  
Pulsed Laser Irradiation

ABSTRACTErbium ions were successfully doped in silicon by pulsed laser irradiation above the threshold laser energy density. Photoluminescence peaks at 1.54, 1.59 and 1.64 µm from Er-optical centers were observed after annealing of Er-doped samples. The intensity of the 1.54 µm Er-emission band increased upon increase in the laser energy density, and then gradually decreased after reaching the maximum, due to the laser sputtering of the silicon substrate. Oxygen atoms, which were unintentionally codoped with Er-ions, were found to be distributed in the same region as in Er-ions, and were suggested to play roles to activate Er-optical centers. The maximum concentration of Er-ions doped in the solid state regime were estimated to be the order of 1018 cm−3 by the Rutherford backscattering measurements.

Laser Energy Dependent Structure of Pulsed Laser Deposited Barium Dititanate Films

2009 ◽  
Vol 66 ◽  
pp. 183-186
Author(s):  
L. Li ◽  
Chuan Bin Wang ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Energy Density ◽  
Surface Morphology ◽  
Pulsed Laser Deposition ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Preferred Orientation ◽  
Laser Deposition ◽  
Laser Energy Density ◽  
Energy Dependent ◽  
Deposited Films

Barium dititanate (BaTi2O5) films were prepared on MgO (100) substrate by pulsed laser deposition under various laser energy densities. The effect of laser energy on crystallinity, orientation and surface morphology was investigated. The preferred orientation of the as-deposited films changes from (710) to (020) with decreasing laser energy, and the surface morphology is different depending on laser energy too. The b-axis oriented BaTi2O5 film could be obtained at the laser energy density of 2J/cm2, where the film shows a dense surface with an elongated granular texture.

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