Time-Resolved Optical Reflectivity and Transmission During Laser-Induced Oxidation of Cadmium Films

1983 ◽  
Vol 29 ◽  
Author(s):  
L. Baufay ◽  
M. Wautelet ◽  
A. Pigeolet ◽  
R. Andrew
Keyword(s):  
Melting Point ◽  
Laser Irradiation ◽  
Oxide Layer ◽  
Probe Beam ◽  
Laser Power ◽  
Time Resolved ◽  
Optical Reflectivity ◽  
Glass Substrates ◽  
Cw Laser

ABSTRACTThe laser-induced oxidation of 2000 Å thick cadmium films on glass substrates is studied by measuring the time-resolved reflectivity and transmission of a probe beam. Under CW laser irradiation, the thickness of the oxide layer is shown to increase linearly with time. Also, the velocity, v, of the CdO-Cd interface increases with increasing laser power, with a step when the melting point of Cd is attained. At the highest powers studied in this work, v varies as v = voexp(−a/P), with vo = 6100 Ås−1 and a=4.8 W.

Cw Laser Annealing of Ion Implanted Oxidized Silicon Layers on Sapphire

1982 ◽  
Vol 13 ◽  
Author(s):  
G. Alestig ◽  
G. HolmÉn ◽  
S. Peterström
Keyword(s):  
Hall Effect ◽  
Laser Irradiation ◽  
Oxide Layer ◽  
Laser Power ◽  
Laser Annealing ◽  
Oxide Thickness ◽  
Sheet Resistivity ◽  
High Activation ◽  
Cw Laser ◽  
Hall Effect Measurements

ABSTRACTCW laser annealing has been performed on silicon on sapphire (SOS) implanted with boron or phosphorus ions to a dose of 1015 ions/cm2 . The laser irradiation was done both with and without an oxide layer on top of the silicon and from both the silicon and the sapphire side. Sheet resistivity and Hall effect measurements were used for the analysis of the samples. Good annealing and high activation of the dopants were obtained for both oxidized and unoxidized SOS. For samples irradiated from the silicon side, the needed laser power changed depending on the thickness of the oxide. For samples irradiated from the sapphire side, the needed laser power was independent of oxide thickness.

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.

Direct Measurement of Cw Laser-Induced Crystal Growth Dynamics by Time-Resolved Optical Reflectivity

1980 ◽  
Vol 1 ◽  
Author(s):  
G.L. Olson ◽  
S.A. Kokorowski ◽  
J.A. Roth ◽  
L.D. Hess
Keyword(s):  
Crystal Growth ◽  
Solid Phase ◽  
Growth Dynamics ◽  
Time Resolved ◽  
Laser Method ◽  
Optical Reflectivity ◽  
Spatially Resolved ◽  
Use Of Time ◽  
Cw Laser

ABSTRACTWe report the use of time-resolved optical reflectivity to directly monitor the dynamics of cw laser-induced solid phase epitaxy (SPE) of thin films. This in situ measurement technique utilizes optical interference effects between light reflected from the surface of a sample and from an advancing interface to provide continuous temporal and spatial resolution of crystal growth processes. SPE growth rates of ionimplanted films which are five orders of magnitude faster than previously observed can be induced and accurately measured with the laser method. Arsenic enhances the SPE rate, and spatially resolved measurements show that the growth rate for arsenic implanted films varies in accordance with the ionimplantation profile. Results are reported for silicon selfimplanted samples with and without subsequent arsenic ion implantation, and for silicon samples directly implanted with arsenic.

Evidence Against a Reduced Melting Temperature in Amorphous Silicon

1981 ◽  
Vol 4 ◽  
Author(s):  
S.A. Kokorowski ◽  
G.L. Olson ◽  
J.A. Roth ◽  
L.D. Hess
Keyword(s):  
Melting Point ◽  
Amorphous Silicon ◽  
Melting Temperature ◽  
Laser Heating ◽  
Crystalline Silicon ◽  
Phase Changes ◽  
Experimental Results ◽  
Melting Point Depression ◽  
Time Resolved ◽  
Cw Laser

ABSTRACTExperimental results are presented which indicate that amorphous silicon does not melt at a temperature significantly lower than the melting point of crystalline silicon (1693°K), contrary to recent reports which suggest a 300 to 500°K melting point depression. Time-resolved optical reflectivity measurements are used to determine the temperature and to investigate phase changes which occur in silicon during cw laser heating. It is shown that amorphous silicon films produced by arsenic implantation into Si(100) do not melt when heated to temperatures in excess of 1600°K. An alternate interpretation of previous work that is consistent with the present findings is proposed.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

scholarly journals Induced Crystallization In CW Laser-Irradiated Sol-Gel Deposited Titania Films

1993 ◽  
Vol 321 ◽  
Author(s):  
Gregory J. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Laser Fluence ◽  
Sol Gel ◽  
Film Stress ◽  
Amorphous Films ◽  
Time Resolved ◽  
Cw Laser ◽  
Residual Film ◽  
Titania Films ◽  
Induced Crystallization ◽  
Nanograin Size

AbstractIsothermal annealing of amorphous TiO2 films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300°C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to density or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress.

Solute Segregation and Dynamics of Solid-Phase Crystallization In in and Sb-Implanted Silicon

1981 ◽  
Vol 4 ◽  
Author(s):  
J. Narayan ◽  
G. L. Olson ◽  
O. W. Holland
Keyword(s):  
Laser Power ◽  
Solid Phase ◽  
Solute Segregation ◽  
Dislocation Loops ◽  
Solid Phase Crystallization ◽  
Time Resolved ◽  
Plan View ◽  
Ion Channeling ◽  
Retrograde Solubility ◽  
Transmission Electron

ABSTRACTTime-resolved-reflectivity measurements have been combined with transmission electron microscopy (cross-section and plan-view), Rutherford backscattering and ion channeling techniques to study the details of laser induced solid phase epitaxial growth in In+ and Sb+ implanted silicon in the temperature range from 725 to 1500 °K. The details of microstructures including the formation of polycrystals, precipitates, and dislocations have been correlated with the dynamics of crystallization. There were limits to the dopant concentrations which could be incorporated into substitutional lattice sites; these concentrations exceeded retrograde solubility limits by factors up to 70 in the case of the Si-In system. The coarsening of dislocation loops and the formation of a/2<110>, 90° dislocations in the underlying dislocation-loop bands are described as a function of laser power.

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.

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