Interface Temperatures and Temperature Gradients in Silicon During Pulsed Laser Irradiation

1988 ◽  
Vol 100 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Heat Flow ◽  
Laser Irradiation ◽  
Thermal Strain ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Temperature Gradients ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Gradients ◽  
Pulsed Laser Irradiation

ABSTRACTNanosecond-resolution x-ray diffraction has been used to measure the interface and lattice temperatures of silicon during rapid, pulsed-laser induced melting and regrowth in silicon. Measurements have been carried out on <100> and <111> oriented silicon using the (100) and (111) reflections to measure the thermal strain during 30 ns, 1.1 J/cm2 KrF laser pulses. The results indicate overheating to be low (< 2 K/m/s) for both orientations with undercooling rates of 5.6 K/m/s and 11.4 K/m/s for the <100> and <111> orientations, respectively. Observations of higher than expected temperature gradients below the liquidsolid interface have been discussed in terms of restricted heat flow under high gradients.

Time-Resolved X-Ray Studies During Pulsed-Laser Irradiation of Ge

1984 ◽  
Vol 35 ◽  
Author(s):  
J.Z. Tischler ◽  
B.C. Larson ◽  
D.M. Mills
Keyword(s):  
Melting Point ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
High Energy ◽  
Measured Temperature ◽  
Time Resolved ◽  
Synchrotron Source ◽  
X Ray ◽  
Pulsed Laser Irradiation

ABSTRACTSynchrotron x-ray pulses from the Cornell High Energy Synchrotron Source (CHESS) have been used to carry out nanosecond resolution measurements of the temperature distrubutions in Ge during UV pulsed-laser irradiation. KrF (249 nm) laser pulses of 25 ns FWHM with an energy density of 0.6 J/cm2 were used. The temperatures were determined from x-ray Bragg profile measurements of thermal expansion induced strain on <111> oriented Ge. The data indicate the presence of a liquid-solid interface near the melting point, and large (1500-4500°C/pm) temperature gradients in the solid; these Ge results are analagous to previous ones for Si. The measured temperature distributions are compared with those obtained from heat flow calculations, and the overheating and undercooling of the interface relative to the equilibrium melting point are discussed.

Overheating and Undercooling in Silicon During Pulsed-Laser Irradiation

1984 ◽  
Vol 35 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Pulsed Laser ◽  
Laser Pulses ◽  
High Energy ◽  
X Ray Diffraction ◽  
Laser Melting ◽  
Time Resolved ◽  
Synchrotron Source ◽  
X Ray ◽  
Krf Excimer Laser ◽  
Pulsed Laser Irradiation

ABSTRACTWe have used time-resolved x-ray diffraction measurements of thermal expansion induced strain to measure overheating and undercooling in <100> and <111> oriented silicon during pulsed laser melting and regrowth. 249 nm (KrF) excimer laser pulses of 1.2 J/cm2 energy density and 25 ns FWHM were synchronized with x-ray pulses from the Cornell High Energy Synchrotron Source (CHESS) to carry out Bragg profile measurements with ±2 ns time resolution. Combined overheating and undercooling values of 120 ± 30 K and 45 ± 20 K were found for the <111> and <100> orientations, respectively, and these values have been used to obtain information on the limiting regrowth velocities for silicon.

Oxidation and Nitridation by Pulsed Laser Irradiation of Solids Immersed in Liquids

1986 ◽  
Vol 75 ◽  
Author(s):  
S. Roorda ◽  
A. Polman ◽  
S. B. Ogale ◽  
F. W. Saris
Keyword(s):  
Laser Irradiation ◽  
Rutherford Backscattering Spectrometry ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Processing Parameters ◽  
Initial Surface ◽  
X Ray Diffraction ◽  
Compound Formation ◽  
Pulsed Laser Irradiation

AbstractNitridation and oxidation of titanium is achieved by pulsed laser irradiation of Ti immersed in liquid ammonia or water. Rutherford Backscattering Spectrometry shows that large amounts of nitrogen and oxygen can be incorporated in the metal surface to a depth of several 1000 Å. X-ray diffraction shows evidence of compound formation. Scanning Electron Microscopy reveals that initial surface texture is smoothed, and that stress induced cracks and holes may appear. Irradiation of Fe and Si immersed in various liquids shows that modification depends on which combination of solid and liquid is used. Influence of processing parameters such as laser-energy density and number of laser pulses on compound formation has been investigated. The process is viewed as a reactive solute incorporation in the laser melted surface layer, followed by compound formation.

scholarly journals Overheating In Silicon During Pulsed-Laser Irradiation?

1985 ◽  
Vol 51 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Laser Irradiation ◽  
Thermal Strain ◽  
Pulsed Laser ◽  
Interface Velocity ◽  
High Energy ◽  
Time Resolved ◽  
Synchrotron Source ◽  
Zero Velocity ◽  
The Difference ◽  
Pulsed Laser Irradiation

ABSTRACTNanosecond resolution time-resolved x-ray diffraction measurements of thermal strain have been used to measure the interface temperatures in silicon during pulsed-laser irradiation. The pulsed-time-structure of the Cornell High Energy Synchrotron Source (CHESS) was used to measure the temperature of the liquid-solid interface of <111> silicon during melting with an interface velocity of 11 m/s, at a time of near zero velocity, and at a regrowth velocity of 6 m/s. The results of these measurements indicate 110 K difference between the temperature of the interface during melting and regrowth, and the measurement at zero velocity shows that most of the difference is associated with undercooling during the regrowth phase.

Time-Resolved X-Ray Absorption of An Amorphous Si Foil During Pulsed Laser Irradiation

1985 ◽  
Vol 51 ◽  
Author(s):  
Kouichi Murakami ◽  
Hans C. Gerritsen ◽  
Hedser Van Brug ◽  
Fred Bijkerk ◽  
Frans W. Saris ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Direct Evidence ◽  
Pulsed Laser ◽  
Time Resolved ◽  
Edge Structure ◽  
X Ray ◽  
Nanosecond Pulsed Laser ◽  
Amorphous Si ◽  
X Ray Absorption ◽  
Pulsed Laser Irradiation

ABSTRACTWe report time-resolved X-ray absorption and extended X-ray absorption fine structure (EXAFS) measurements on amorphous silicon under nanosecond pulsed-laser irradiation. Each measurement was performed with one laser shot in the X-ray energy range from 90 to 300 eV. An X-ray absorption spectrum for induced liquid Si (liq*Si) was first observed above an energy density of 0.17 J/cm2. It differs significantly from the spectrum for amorphous Si and characteristically shows the disappearance of the Si-L(II,III) edge structure at around 100 eV. This phenomenon is interpreted in terms of a significant reduction in the 3s-like character of the unfilled part of the conduction band of liq*Si compared to that of amorphous Si. This is the first direct evidence that liq*Si has a metallic-like electronic structure. Timeresolved EXAFS results are also discussed briefly.

Nanosecond resolution time-resolved x-ray study of silicon during pulsed-laser irradiation

1986 ◽  
Vol 1 (1) ◽  
pp. 144-154 ◽  
Author(s):  
B. C. Larson ◽  
J. Z. Tischler ◽  
D. M. Mills
Keyword(s):  
Laser Irradiation ◽  
Irradiation Time ◽  
Pulsed Laser ◽  
High Energy ◽  
Resolution Time ◽  
Time Resolved ◽  
Synchrotron Source ◽  
X Ray ◽  
Temperature Distributions ◽  
Pulsed Laser Irradiation

We have used the pulsed time structure of the Cornell High-Energy Synchrotron Source (CHESS) to carry out a nanosecond resolution time-resolved x-ray study of silicon during pulsed-laser irradiation. Time-resolved temperature distributions and interfacial overheating and undercooling were measured on 〈111〉 and 〈100〉 silicon during 25 ns UV laser pulses through the analysis of thermal expansion induced strain. The temperature gradients were found to be > 107 K/cm at the liquid-solid interface and the temperature distributions have been shown to be in agreement with numerical heat flow calculations for these laser conditions. The combined overheating and undercooling (during ∼ 10 m/s melting and ∼ 6 m/s regrowth) was measured to be 110 ± 30 K on 〈111〉 oriented silicon and 50 ± 25 K on 〈100〉 silicon. These values have been interpreted in terms of velocity coefficients of overheating and undercooling.

SUPERCONDUCTING Bi-Sr-Ca-Cu-O THIN FILMS PREPARED BY THE PULSED-LASER EVAPORATION

1988 ◽  
Vol 02 (08) ◽  
pp. 999-1003
Author(s):  
F.M. ZHANG ◽  
Y.C. ZHANG ◽  
S.J. GU ◽  
Y.L. ZHOU ◽  
Z.H. CHEN ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Nd:Yag Laser ◽  
Pulse Width ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Laser Evaporation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zero Resistance

We report here the preparation of the superconducting Bi-Sr-Ca-Cu-O thin films on SrTiO 3(100) substrates by a Nd:YAG laser, which provides laser pulses with wavelength of 1.06µm and pulse width of 200ns. After the heat treatment at 850°C for half an hour in oxygen flow, the samples exhibit superconductivity with the zero resistance at 66.8K and the onset temperature around 84K. X-ray diffraction analyses show that the samples have the preferred orientation with the c-axis perpendicular to the substrate.

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