The Origin and Implications of (111)-Textured Grains Obtained via Nucleation and Growth of Solids in Pulsed-Laser-Quenched Al Films on SiO2

2006 ◽  
Vol 979 ◽  
Author(s):  
J. B. Choi ◽  
Min H. Choi ◽  
U.-J. Chung ◽  
A. B. Limanov ◽  
James S. Im
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Heterogeneous Nucleation ◽  
Microstructural Analysis ◽  
Pulsed Laser ◽  
Nucleation And Growth ◽  
Nucleation Model ◽  
Wide Energy ◽  
Excimer Laser Irradiation ◽  
Condensed Systems

AbstractWe have investigated excimer laser irradiation of 2000-Å-thin as-deposited Al films on SiO2. Microstructural analysis of the irradiated films conducted with AFM and EBSD techniques reveals that there exists a wide energy density interval over which large equaxed grains with a strong (111) texture are obtained. Based on thermal, transformational, and microstructural considerations, we propose a heterogeneous nucleation model to account for the observed behaviors, and discuss the implication of the model on the phenomenon of heterogeneous nucleation of crystalline solids in condensed systems as regards the thermodynamic role played by the orientation of subcritical clusters.

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.

Plasma Dynamics During Pulsed Laser Evaporation of High Tc Superconductors

1990 ◽  
Vol 201 ◽  
Author(s):  
Rajiv K. Singh ◽  
R. Neifeld ◽  
J. Narayan
Keyword(s):  
Theoretical Model ◽  
Energy Density ◽  
Excimer Laser ◽  
Pulsed Laser ◽  
Laser Wavelength ◽  
Laser Evaporation ◽  
Degree Of Ionization ◽  
Plasma Dynamics ◽  
Excimer Laser Irradiation

AbstractWe have theoretically and experimentally investigated the dynamics of the evaporated material generated by nanosecond excimer laser irradiation of YBa2Cu3O7 targets in vacuum. The velocity distribution and the ionization of the plasma were determined by the ion time of flight measurements. The excimer laser ablated species possessed very high velocities (> 106 cm/sec) which increased non-linearly with energy density. The ionization/ volume of the evaporated material exhibited a weak dependence on energy density, thereby suggesting the role of nonthermal mechanisms in the ionization process. These experimental results have been correlated with the theoretical model analyzing the plasma dynamics during pulsed laser evaporation of materials. A new modification to the earlier theoretical model is developed which accurately predicts the terminal velocities and the effect of ionization on these velocities. Various factors including, evaporation rates, degree of ionization, and laser wavelength which affect the plasma velocities will also be discussed.

Doping of GaAs From Silane Decomposition Under Pulsed Laser Irradiation

1983 ◽  
Vol 29 ◽  
Author(s):  
D. Pribat ◽  
D. Dieumegard ◽  
B. Dessertenne ◽  
J. Chaplart
Keyword(s):  
High Pressure ◽  
Energy Density ◽  
Laser Irradiation ◽  
Sheet Resistance ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Compensation Mechanism ◽  
Yag Laser ◽  
Oxygen Penetration ◽  
Pulsed Laser Irradiation

ABSTRACTWe have studied silicon incorporation in GaAs subsequent to Nd-YAG laser irradiation through high pressure silane atmospheres. The process involves SiH4 pyrolysis at contact with a laser-melted GaAs surface, and incorporation of the released Si atoms in the melt. SIMS analyses have allowed us to study silicon incorporation as a function of SiH4 pressure, laser energy density and number of laser shots. The high sheet resistance of the doped layers indicates that the silicon atoms are poorly electrically activated. A compensation mechanism is discussed based on oxygen penetration from native GaAs oxide layers.

The Initial Stages of Silicide Epitaxy - Nucleation and Morphology

1987 ◽  
Vol 94 ◽  
Author(s):  
R. J. Nemanich ◽  
C. M. Doland ◽  
F. A. Ponce
Keyword(s):  
Heterogeneous Nucleation ◽  
Cluster Size ◽  
Critical Thickness ◽  
Nucleation And Growth ◽  
Silicide Formation ◽  
Initial Thickness ◽  
Critical Cluster ◽  
Compound Formation ◽  
Nucleation Model ◽  
Metal Overlayers

ABSTRACTThe initial stages of epitaxial silicide formation are described in terms of the nucleation properties. The reaction process is divided into the stages of interdiffusion, nucleation, and growth and coalescence. The aspects of the nucleation from the interdiffused regions are described. Results are presented for Pd and Pt deposited on clean Si surfaces. The initial thickness where silicide compound formation is observed is related to he critical cluster size of the nucleation model. The epitaxial morphology can be strongly influenced by heterogeneous nucleation involving the substrate interface, and this effect is demonstrated by reaction with metal overlayers less than the critical thickness.

Excimer Laser Irradiation of Metallic Films on Ceramic Substrates

1991 ◽  
Vol 235 ◽  
Author(s):  
M. J. Godbole ◽  
A. J. Pedraza ◽  
D. H. Lowndes ◽  
J. R. Thompson
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Surface Region ◽  
Copper Films ◽  
Metallic Films ◽  
Ceramic Substrates ◽  
Near Surface ◽  
Excimer Laser Irradiation ◽  
Sputter Deposited ◽  
Density Threshold

ABSTRACTCopper films sputter deposited on mechanically polished (optical finish) and on annealed substrates were laser-irradiated at various energy densities. The effect of the substrate condition on both the evaporation threshold and the morphology of the laser-irradiated metallic films was investigated. The energy density threshold for laser-induced evaporation of the copper films was studied using energy dispersive x-ray spectroscopy (EDS) in a scanning electron microscope (SEM). It was found that for annealed substrates the energy density threshold decreases relative to the threshold for the as-polished condition. These results are compared with predictions of a mathematical model that assumes that the near surface region of the as-polished ceramic is a highly damaged region and, thus, constitutes a thermal barrier. The film remains intact and with almost no change in morphology after laser irradiation at energy densities lower than 0.80 J/cm2 if the substrate has been previously annealed. On the other hand, copper films deposited on as-polished substrates break up during laser processing forming copper islands.

Effects of laser irradiation energy density on the properties of pulsed laser deposited ITO thin films

2005 ◽  
Vol 81 (5) ◽  
pp. 953-957 ◽  
Author(s):  
F.O. Adurodija ◽  
R. Brüning ◽  
I.O. Asia ◽  
H. Izumi ◽  
T. Ishihara ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Density ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Irradiation Energy ◽  
Ito Thin Films ◽  
Irradiation Energy Density

Formation of polytype microstructure in pulsed-laser-irradiated sapphire substrates

1995 ◽  
Vol 53 ◽  
pp. 344-345
Author(s):  
Siqi Cao ◽  
A. J. Pedraza ◽  
L. F. Allard ◽  
D. H. Lowndes
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Electroless Deposition ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Surface Modifications ◽  
Near Surface ◽  
Sapphire Substrates ◽  
Hcp Structure ◽  
Pulsed Laser Irradiation

Surface modifications of wide-gap materials are produced by pulsed laser irradiation. Under given conditions, these near-surface modifications can promote adhesion enhancement of deposited thin film materials, and activation for electroless deposition. AIN decomposes during laser irradiation leaving a metallic film on the surface. High density dislocations were observed in the surface layer of AIN that was laser melted but not decomposed. The laser melted alumina becomes amorphous at a laser energy density of ~1J/cm2. In sapphire, γ-alumina is formed when the sample is laser irradiated in Ar/4%H2. Here, we report the formation of a new structure in laser-irradiated sapphire.Optically polished c-axis sapphire substrates were laser-irradiated in an Ar/4%H2 atmosphere at 4J/cm2 energy density, using a 308 nm-wavelength laser with a pulse duration of ~40 ns. Sapphire (A12O3) has a space group R 3 c and can be described as an hcp structure having oxygen and aluminum layers alternately stacking along the c-axis.

Formation Of A Metastable Nisi Phase On Si Induced By Pulsed Laser Irradiation

1987 ◽  
Vol 91 ◽  
Author(s):  
F. Priolo ◽  
P. Baeri ◽  
M.G. rimaldi ◽  
E. Rimini
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Rutherford Backscattering Spectrometry ◽  
Pulsed Laser ◽  
Surface Melting ◽  
Yield Reduction ◽  
Density Range ◽  
Appreciable Change ◽  
Nisi Phase ◽  
Pulsed Laser Irradiation

ABSTRACTThermally grown NiSi layers on <111> Si substrates were irradiated by 35 nsec Nd glass laser pulses in the energy density range 0.3−2.0 J/cm2. Time resolved reflectivity measurements were performed during the irradiation to detect surface melting. The samples were analyzed by 2.0 MeV He+ Rutherford Backscattering Spectrometry in combination with channeling effect. The measured threshold for surface melting was 0.5 J/cm2. Irradiation at energy densities higher than 1.3 J/cm2 changed the silicides layer composition because of the mixing with the underlying silicon. In the intermediate energy density range (0.7−1.1 J/cm ) slight changes in composition were observed, a strong alignement of NiSi molecules along the <111> substrate direction was however observed. The measured Xmin was about 30%. It seems then that an epitaxial NiSi phase can be grown by pulsed laser irradiation with a suitable choice of the incident energy density. Work is in progress to identify this new NiSi phase by TEM. However this ordered phase is a metastable one since after anunealing at 250°C, 30min the channeling yield reduction disappeared without any appreciable change in composition.

Time Resolved Reflectivity Measurements on Pulsed Laser Irradiated Silicon Immersed in Water

1988 ◽  
Vol 100 ◽  
Author(s):  
X. D. Wu ◽  
D. Dijkkamp ◽  
T. Venkatesan
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Incident Energy ◽  
Pulsed Laser ◽  
Water Layer ◽  
Absorbed Energy ◽  
Time Resolved ◽  
Starting Point ◽  
Melt Duration ◽  
Pulsed Laser Irradiation

ABSTRACTTime resolved reflectivity (TRR) measurements were carried out during pulsed laser irradiation of silicon immersed in water. It was found that the TRR in water was similar to that in air though the signal deteriorated after about 100 ns from the starting point of the laser for incident energy densities above 1.4 J/cm2 (unlike what is observed in air). The total melt duration in water was about 2.8 to 1.6 times less than that in air at the same absorbed energy density. It was estimated that 20 % of the absorbed energy was taken away by the water layer. For the same energy coupled into the solid the melt-in/regrowth kinetics was speeded up by the presence of the water layer at the surface by about a factor 2 consistant with the results of Polman et. a15.

Copper ohmic contacts to n-type SiC formed with pulsed excimer laser irradiation

2001 ◽  
Vol 680 ◽  
Author(s):  
K. Abe ◽  
M. Sumitomo ◽  
O. Eryu ◽  
K. Nakashima
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Excimer Laser ◽  
Ohmic Contacts ◽  
Laser Energy ◽  
Contact Layer ◽  
Ohmic Behavior ◽  
Current Voltage ◽  
Excimer Laser Irradiation ◽  
Current Voltage Characteristics

ABSTRACTCopper-based ohmic contacts to n-type 6H-SiC have been investigated. In this study, ohmic contacts have been fabricated with pulsed excimer laser irradiation to Cu-deposited substrates at room temperature. It is shown that current-voltage characteristics depend on the laser energy density. Contacts formed by the laser irradiation at the energy density above 1.2 J/cm2 have shown the ohmic behavior. Cu atoms have slightly diffused into SiC by the laser irradiation at 1.4 J/cm2. As a result, a thin ohmic contact layer has been obtained by the laser processing. AES and XRD study have revealed that a Cu-SiC alloy containing Cu silicide (Cu3Si) is formed by the laser irradiation.

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