Raman Spectroscopy Study of Pulsed Laser Induced Structural Transformations in Amorphous Ge Films

1995 ◽  
Vol 397 ◽  
Author(s):  
C. García ◽  
A.C. Prieto ◽  
J. Jiménez ◽  
J. Siegel ◽  
J. Solís ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Crystallization Process ◽  
Bond Angle ◽  
Pulsed Laser ◽  
Picosecond Laser ◽  
Laser Pulses ◽  
Structural Transformations ◽  
Spectroscopy Study ◽  
Glass Substrates ◽  
Average Bond

ABSTRACTStructural transformations induced in amorphous Ge films by picosecond laser pulses are studied by means of Raman spectroscopy and their dependence on parameters like the pulse fluence or the thermal conductivity of the substrate are analyzed. A correlation length model is used for studying the crystallization process, while the average bond angle distortion is used for determining the state of relaxation of the amorphous phase. Silicon and glass substrates are compared.

Nanocrystalline Ge Synthesis by Picosecond Pulsed Laser Induced Melting and Rapid Soldddtcation

1996 ◽  
Vol 452 ◽  
Author(s):  
J. Solis ◽  
J. Siegel ◽  
C. Garcia ◽  
J. Jimenez ◽  
R. Serna
Keyword(s):  
Crystallite Size ◽  
Amorphous Matrix ◽  
Pulsed Laser ◽  
Picosecond Laser ◽  
Laser Pulses ◽  
Correlation Lengths ◽  
Glass Substrates ◽  
Solidification Kinetics ◽  
Rapidly Solidified ◽  
Nm Range

AbstractMelting and rapid solidification has been induced in DC-sputtered amorphous Ge (a-Ge) films on glass substrates by irradiation with picosecond laser pulses at 583 nm. The melting-solidification kinetics has been followed by means of real time reflectivity measurements with ns resolution and the structure of the rapidly solidified material has been analyzed by means of Raman spectroscopy in micro-Raman configuration. The results obtained show that for laser pulse fluences above a certain threshold recalescence occurs during solidification leading to the formation of nanocrystalline Ge embedded in an amorphous matrix. The phonon correlation length (L) obtained from the Raman spectra of the irradiated regions has been used to analyze the evolution of the crystallite size with the laser fluence. For low fluences above the recalescence threshold, the values of L are in the 8–10 nm range. However, if the fluence is sufficiently increased, the crystallite size shows a clear linear dependence on the fluence with phonon correlation lengths scaling from 6 to 13 nm.

Growth and Characterization of Urea Doped p-Type ZnO Thin Film Grown by Pulsed Laser Deposition

2009 ◽  
Vol 67 ◽  
pp. 127-130 ◽  
Author(s):  
Majumdar Sayanee ◽  
Banerji Pallab
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Laser Deposition ◽  
Zno Films ◽  
Group V ◽  
Xrd Pattern ◽  
Glass Substrates ◽  
P Type

In the present study we have used urea as the source for doping nitrogen in ZnO since the most successful acceptor type dopant is the group V element like nitrogen. The nitrogen doped ZnO films have been deposited on glass substrates using Pulsed Laser Deposition technique using 248 nm KrF laser at energy 300 mJ by varying the number of laser pulses with a repetition rate of 10 pulse/sec in vacuum (10-6 mbar) at a constant temperature of 300 °C. The XRD pattern confirms the formation of wurtzite structure of ZnO, which is polycrystalline in nature. We have also performed UV absorption spectroscopy and the band gap is found to be 3.4 eV. Resistivity of the film increases with the increase of thickness for the undoped ZnO samples where the carrier concentrations are found to be of the order of 1017 cm-3. The mobility of the as-grown film is found to be 24.9 cm2/V-s. After doping with nitrogen the carrier concentration drops to the order of 1015 cm-3 and the mobility becomes 1.5 cm2/V-s. The mobility slightly varies with thickness. The resistivity increases to 1.3 KΩ-cm and the film shows p-type behavior. The results are explained on the basis of the available theory.

Low Temperature Crystallization of PbTiO3 Thin Film by Excimer Laser Irradiation

1999 ◽  
Vol 596 ◽  
Author(s):  
T. Mihara ◽  
S Mochizuki ◽  
T. Ishida ◽  
Y Sato ◽  
J. Nishii
Keyword(s):  
Perovskite Structure ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Glass Substrates ◽  
Structure Morphology ◽  
Excimer Laser Irradiation ◽  
Low Temperature Crystallization ◽  
Temperature Crystallization

AbstractLowering the fabrication temperature for ferroelectric films is very important not only for silicon monolithic circuits but also for various substrates. Amorphous PbTiO3 thin films were prepared on glass substrates using ArF pulsed laser deposition (PLD). They were subsequently treated by a laser-induced phase transformation technique to achieve a perovskite structure. After irradiation by an ArF pulsed laser with an energy density 50mJ/cm2 in air, the films crystallized into the perovskite structure. It was possible to maintain the substrate at room temperature during the whole fabrication process. The structure, morphology and composition of the films were characterized by X-ray diffraction diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The surface of film irradiated with a laser was often rather rough and peeled off everywhere. It was necessary to control the number of laser pulses to avoid damaging the films. The effects of chemical composition and fabrication temperature are also discussed.

Structural Analysis of Carbon Thin Films Deposited by Pulsed Laser Deposition

1992 ◽  
Vol 285 ◽  
Author(s):  
M.A. Capano ◽  
F. Qian ◽  
R.K. Singh ◽  
N.T. Mcdevitt
Keyword(s):  
Raman Spectroscopy ◽  
Bond Angle ◽  
Pulsed Laser ◽  
Domain Size ◽  
Carbon Films ◽  
Maximum Density ◽  
Laser Deposition ◽  
Density Measurements ◽  
X Ray ◽  
Si Substrates

ABSTRACTThe objective of the current study is to gain a greater understanding of the atomic structure of carbon films deposited by UV-pulsed-laser ablation. Films deposited onto Si substrates at 293 K, 473 K, 673 K, and 873 K are characterized using X-ray reflectometry and Raman spectroscopy. Film densities are shown to initially decrease from a maximum density of 2.39 g/cm3 as temperature increases. Above 673 K the density remains constant. When compared with Raman spectroscopy data, the reflectometry data are shown to be sensitive to microstructural changes within the films. The possibility of using density measurements as a boundary condition for more quantitative analysis is discussed. Also, Raman spectroscopy indicates that the graphitic domain size initially decreases, passes through a minimum, and then increases as temperature increases. The amount of bond-angle disorder is shown to decrease with increasing substrate temperature. However, an upward shift in frequency of the Raman D peak is not observed with the presumed decrease in sp3 bonding as the deposition temperature increases. These and other experimental results are presented and discussed.

Transient Structural Relaxation and Melting Temperature of Amorphous Silicon

1988 ◽  
Vol 100 ◽  
Author(s):  
W. C. Sinke ◽  
T. Warabisako ◽  
M. Miyao ◽  
T. Tokuyama ◽  
S. Roorda ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Amorphous Silicon ◽  
Laser Irradiation ◽  
Heating Rate ◽  
Melting Temperature ◽  
Structural Relaxation ◽  
Strain Energy ◽  
Bond Angle ◽  
Random Network ◽  
Average Bond

ABSTRACTThe structure of ion-implanted a-Si has been studied using Raman spectroscopy. It is shown that the average bond-angle distortion and the strain energy stored in the random network vary drastically upon annealing. Relaxation is enhanced in the case of heating by laser irradiation. The results imply that the apparent melting temperature of a-Si may vary from one experiment to another, depending on the heating rate and -method.

Picosecond Single-Photon and Femtosecond Two-Photon Pulsed Laser Stimulation for IC Characterization and Failure Analysis

2009 ◽  
Author(s):  
V. Pouget ◽  
E. Faraud ◽  
K. Shao ◽  
S. Jonathas ◽  
D. Horain ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Single Photon ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Laser Stimulation ◽  
Two Photon ◽  
Resolution Improvement ◽  
Ultrashort Laser

Abstract This paper presents the use of pulsed laser stimulation with picosecond and femtosecond laser pulses. We first discuss the resolution improvement that can be expected when using ultrashort laser pulses. Two case studies are then presented to illustrate the possibilities of the pulsed laser photoelectric stimulation in picosecond single-photon and femtosecond two-photon modes.

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