Transport Phenomena and Droplet Formation During Pulsed Laser Interaction With Thin Films

2000 ◽  
Vol 122 (4) ◽  
pp. 763-770 ◽  
Author(s):  
D. A. Willis ◽  
X. Xu
Keyword(s):  
Thin Films ◽  
Surface Topography ◽  
Surface Deformation ◽  
Laser Energy ◽  
Transport Phenomena ◽  
Pulsed Laser ◽  
Target Material ◽  
Droplet Formation ◽  
Laser Interaction ◽  
Transient Field

This work investigates transport phenomena and mechanisms of droplet formation during a pulsed laser interaction with thin films. The surface of the target material is altered through material flow in the molten phase induced by a tightly focused laser energy flux. Such a process is useful for developing a laser-based micromachining technique. Experimental and numerical investigations of the laser-induced fluid flow and topography variations are carried out for a better understanding of the physical phenomena involved in the process. As with many machining techniques, debris is often generated during laser-material interaction. Experimental parametric studies are carried out to correlate the laser parameters with the topography and droplet formations. It is found that a narrow range of operation parameters and target conditions exists for “clean” structures to be fabricated. The stop action photography technique is employed to capture the surface topography variation and the melting development with a nanosecond time resolution and a micrometer spatial resolution. Numerical simulations of the laser-induced surface deformation are also performed to obtain the transient field variables and to track the deforming surface. The comparison between the numerical and experimental work shows that, within the energy intensity range investigated in this work, the surface deformation and droplet formation are attributed to the surface-tension-driven flow, and the recoil pressure effect plays an insignificant role in the surface topography development. [S0022-1481(00)02903-0]

Epitaxial Growth of AlN Thin Films on Silicon and Sapphire by Pulsed Laser Deposition

1995 ◽  
Vol 395 ◽  
Author(s):  
R.D. Vispute ◽  
H. Wu ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Pulsed Laser Deposition ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Breakdown Field ◽  
Transmission Electron ◽  
Uv Visible ◽  
Relationship Of

ABSTRACTAIN thin films have been grown epitaxially on Si(111) and Al2O3(0001) substrates by pulsed laser deposition. These films were characterized by FTIR and UV-Visible, x-ray diffraction, high resolution transmission electron and scanning electron microscopy, and electrical resistivity. The films deposited on silicon and sapphire at 750-800°C and laser energy density of ∼ 2 to 3J/cm2 are epitaxial with an orientational relationship of AIN[0001]║ Si[111], AIN[2 110]║Si[011] and AlN[0001]║Al2O3[0001], AIN[1 2 1 0]║ Al2O3[0110] and AIN[1010] ║ Al2O3[2110]. The both AIN/Si and AIN/Al2O3 interfaces were found to be quite sharp without any indication of interfacial reactions. The absorption edge measured by UV-Visible spectroscopy for the epitaxial AIN film grown on sapphire was sharp and the band gap was found to be 6.1eV. The electrical resistivity of the films was about 5-6×l013Ω-cm with a breakdown field of 5×106V/cm. We also found that the films deposited at higher laser energy densities ≥10J/cm2 and lower temperatures ≤650°C were nitrogen deficient and containing free metallic aluminum which degrade the microstructural, electrical and optical properties of the AIN films

Pulsed Laser Deposition (PLD) Technique to Prepare Biocompatible Thin Films

2006 ◽  
Vol 49 ◽  
pp. 56-61 ◽  
Author(s):  
Joseph J. Beltrano ◽  
Lorenzo Torrisi ◽  
Anna Maria Visco ◽  
Nino Campo ◽  
E. Rapisarda
Keyword(s):  
Thin Films ◽  
Pulsed Laser ◽  
Target Material ◽  
Xrd Analysis ◽  
Spot Size ◽  
Laser Deposition ◽  
Laser Source ◽  
Medical Field ◽  
Hot Plasma ◽  
532 Nm

A Nd:YAG laser is employed to ablate different materials useful in the bio-medical field. The laser source operates in the IR (1064 nm), VIS (532 nm) and UV (355 nm) regions with a pulse duration of 3-9 ns, a pulse energy of 3-300 mJ, a spot size of 1 mm2 and a repetition rate of 1- 30 Hz. Target material of interest are Titanium, Carbon, Hydroxyapatite (HA) and Polyethylene (PE). Laser irradiation occurs in vacuum, where hot plasma is generated, and thin films are deposited on near substrates. Generally, substrates of silicon, titanium, titanium-alloys and polymers were employed. Biocompatible thin films are investigated with different surface techniques, such as IR spectroscopy, Raman spectroscopy, XRD analysis and SEM investigations. Depending of the kind of possible application, films require special properties concerning the grain size, porosity, uniformity, wetting, hardness, adhesion, crystallinity and composition. The obtained results will be presented and discussed with particular regard to HA..

Structural damage of Bacillus subtilis biofilms using pulsed laser interaction with gold thin films

2016 ◽  
Vol 10 (8) ◽  
pp. 1043-1052
Author(s):  
Judith Krawinkel ◽  
Maria Leilani Torres-Mapa ◽  
Eisha Mhatre ◽  
Ákos T. Kovács ◽  
Alexander Heisterkamp
Keyword(s):  
Thin Films ◽  
Bacillus Subtilis ◽  
Structural Damage ◽  
Pulsed Laser ◽  
Laser Interaction ◽  
Gold Thin Films

Computer Simulation of Pulsed Laser Ablation for YBaCuO Superconducting Films

1990 ◽  
Vol 191 ◽  
Author(s):  
Toshiyuki Nakamiya ◽  
Kenji Ebihara ◽  
P. K. John ◽  
B. Y. Tong
Keyword(s):  
Thin Films ◽  
Excimer Laser ◽  
Laser Energy ◽  
Pulsed Laser ◽  
The Finite Element Method ◽  
High Tc ◽  
One Dimensional ◽  
Incident Laser Energy ◽  
Krf Excimer Laser ◽  
Pulsed Laser Irradiation

ABSTRACTThe dynamics of melting and ablation of high Tc YBa2Cu3O7-x superconducting thin films flashed by a pulsed KrF excimer laser(λ=248nm) or a pulsed Nd-YAG laser (λ =1.06μ m) were studied numerically. The fundamental model during a pulsed laser irradiation was a one-dimensional heat conduction equation. The finite element method was applied to solve the equation including the temperature dependence of the thermal conductivity of YBaCuO thin films. In addition, the microstructure of YBa2Cu3O7-x bulk(l.5mm thick) flashed by a pulsed XeCl excimer laser (λ =308nm) was investigated by scanning electron microscopy (SEM) in order to estimate the threshold incident laser energy density for surface melting and ablation. The good agreements between the numerical calculations and the experimental results were obtained.

Spectroscopic Ellipsometry Characterization of La2Ti2O7 Thin Films

1994 ◽  
Vol 361 ◽  
Author(s):  
Bryan D. Dickerson ◽  
Masaya Nagata ◽  
Y.J. Song ◽  
H.D. Nam ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Substrate Material ◽  
Index Of Refraction ◽  
Laser Deposition ◽  
Energy Substrate ◽  
Fabrication Parameters ◽  
Cauchy Model

ABSTRACTOptical properties of La2Ti2O7 thin films were investigated by spectroscopie ellipsometry and compared to those of bulk sintered ceramics. Thin films were prepared by pulsed laser deposition (PLD) from bulk targets. To separate the effects of thickness, porosity, and index of refraction on observed Ψ and δspectra in thin films, a Cauchy model for n vs. λ was developed from sintered samples, with known porosity. Assuming the effective bulk index of refraction followed the rule of mixtures, corrected models for La2Ti2O7 without porosity were used to determine thickness and porosity of thin films as a function of fabrication parameters such as laser energy, substrate material and temperature. Ellipsometry models were tested and refined through XRD, EDX, ESCA, and SEM.

DEPOSITION OF TiAlV THIN FILMS BY PULSED LASER AND DC MAGNETRON SPUTTERING: STRUCTURAL, COMPOSITIONAL AND ELECTROCHEMICAL CORROSION STUDY

2019 ◽  
Vol 27 (08) ◽  
pp. 1950188
Author(s):  
A. ALKHAWWAM ◽  
B. ABDALLAH ◽  
A. K. JAZMATI ◽  
M. TOOTANJI ◽  
F. LAHLAH
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Corrosion Test ◽  
Pulsed Laser ◽  
Electrochemical Corrosion ◽  
Target Material ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Film Properties ◽  
X Ray

In this work, TiAlV thin films have been prepared on two different types of substrates: silicon and stainless steel (SS304) by two deposition methods: Pulsed Laser Deposition (PLD) and DC magnetron sputtering. Different techniques have been employed in order to characterize film properties such as: Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX), X-ray diffraction (XRD), microhardness and corrosion test. EDX analysis showed that the deposited films are slightly different from that of the target material Ti6Al4V alloy. The measured microhardness values are about 11.7[Formula: see text]GPa and 4.7[Formula: see text]GPa for films prepared by PLD and DC magnetron sputtering, respectively. Corrosion test indicated that the corrosion resistance of the two TiAlV films deposited on SS304 substrates in (0.9% NaCl) physiological normal saline medium was significantly improved compared with the SS304 substrates. These attractive results could permit applications of our films in the medical implants fabrication.

Early stages of the growth of BaTiO3 thin films studied by Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 706-707
Author(s):  
M. Grant Norton ◽  
Gerald R. English ◽  
Christopher Scarfone ◽  
C. Barry Carter
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Room Temperature ◽  
High Temperature Superconductors ◽  
Pulsed Laser ◽  
Target Material ◽  
Pulsed Laser Ablation ◽  
Cubic Phase ◽  
Transmission Electron ◽  
Tetragonal Form

Barium titanate (BaTiO3) may be used in a number of thin-film applications in electronic and optoelectronic devices. For these devices the formation of epitactic films of the correct stoichiometry and phase is essential. In particular, the tetragonal form of BaTiO3, which is stable at room temperature, exhibits ferro-, pyro- and piezoelectric properties. It is desirable to form films of the tetragonal phase directly and thus to avoid formation of either amorphous or polycrystalline material or to form material of the non-ferroelectric cubic phase. Recently two techniques, pulsed-laser ablation and reactive evaporation, have been used to form BaTiO3 thin-films. In the present study BaTiO3 thin-films have been formed using the pulsed-laser ablation technique. Pulsed-laser ablation is now widely used to produce thin-films of the high temperature superconductors and has many advantages over other techniques, in particular the formation of films which maintain the stoichiometry of the target material and by controlling the processing conditions the formation of films having defined crystalline phases.

Numerical Simulation on Short Pulsed Laser Heating of Semiconductor Thin Films: The Case of GaAs

2006 ◽  
Author(s):  
Gary J. Cheng ◽  
Daniel Pirzada ◽  
Xin Ai ◽  
Ben Li
Keyword(s):  
Heat Transfer ◽  
Thin Films ◽  
Numerical Simulation ◽  
Heat Conduction ◽  
Pulse Duration ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Heat Propagation ◽  
Hyperbolic Heat Conduction ◽  
Phase Lag

The results of numerical simulation of heat transfer phenomena in GaAs thin films irradiated by a pulsed laser are presented. A numerical algorithm involving a discontinuous Galerkin finite element method for the solution of hyperbolic heat conduction is used to solve the dual-phase-lag heat conduction equation The effects of different process parameters on heat propagation are analyzed. The heat conduction mode after pulsed laser irradiation is strongly dependent upon the incident laser energy density, film thickness and pulse duration. The heat transfer behavior for nano-, pico- and femto- second pulses has been studied and compared. A wave-type heat transfer phenomena was observed when pulse duration is of the order of relaxation time of the material being heated. It was found that for sub-picosecond pulses, the heat transfer occurs only by a thermal shock wave.

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