Correlation of Raman Spectra and Bonding in DLC Films Deposited by Laser Ablation and Laser-Plasma Ablation Techniques

1991 ◽  
Vol 250 ◽  
Author(s):  
A. Rengan ◽  
J. Narayan ◽  
J. L. Park
Keyword(s):  
Laser Ablation ◽  
Laser Plasma ◽  
Deposition Temperature ◽  
Plasma Deposition ◽  
Raman Shift ◽  
Plasma Ablation ◽  
Valence Electrons ◽  
Diamondlike Carbon ◽  
Plasma Deposited Films ◽  
Deposited Films

AbstractWe have deposited diamondlike carbon (DLC) films on a variety of substrates from 250° C and higher. The effects of deposition temperature on the properties of DLC films deposited by a conventional laser ablation technique are compared with that of a unique laser-plasma deposition scheme. The calculated values of neff, the effective number of valence electrons, suggest that, with the increase in the deposition temperature, the diamondlike component (sp3 bonds) remains invariant for the laser deposited samples, and increases for the laser-plasma deposited films. Raman measurements show that the Raman allowed ‘G’ band upshifts to ˜1600 cm−1 for both deposition schemes. However, the disorder induced 'D' band remains invariant at ˜1370 cm−2 for the laser ablated samples, and downshifts to ˜1350 cm−1 for the laser-plasma deposited samples. These results suggest a correlation between the diamondlike content (sp3 bonds) and the Raman shift of the ‘D’ band.

Models of laser plasma ablation. Part 4. Steadystate theory: collisional absorption flow

1993 ◽  
Vol 49 (2) ◽  
pp. 295-316 ◽  
Author(s):  
G. J. Pert
Keyword(s):  
Laser Ablation ◽  
Laser Plasma ◽  
Thermal Conduction ◽  
Plasma Heating ◽  
Scaling Relations ◽  
Plasma Interaction ◽  
Laser Plasma Interaction ◽  
Plasma Ablation ◽  
Complete Set ◽  
Dimensional Argument

The clarification of models of laser ablation by plasma heating is examined using a general dimensional argument and introducing a set of universal parameters. The regime of laser-plasma interaction in which collisional absorption and thermal conduction dominate is examined for spherical systems. Detailed scaling relations are derived for uninhibited and flux-limited thermal conduction. The complete set of regimes for steady spherical flow are examined, and it is found that the most important flows are thin collisional and thick local absorption.

A comparative study on as-deposited and in situ oxidized ZnO/diamondlike carbon (DLC) nanocomposite by pulsed laser deposition technique

2010 ◽  
Vol 25 (5) ◽  
pp. 899-909 ◽  
Author(s):  
Yuan M. Foong ◽  
Angel T.T. Koh ◽  
Jovan Hsieh ◽  
Daniel H.C. Chua
Keyword(s):  
Laser Ablation ◽  
Photoelectron Spectroscopy ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Deposition Mechanism ◽  
X Ray ◽  
Transmission Electron ◽  
Diamondlike Carbon ◽  
Deposited Films

As-deposited ZnO/diamondlike carbon (DLC) was prepared using the laser ablation technique on ZnO/C targets, and in situ oxidized ZnO/DLC was prepared by using the same technique, but with the presence of oxygen on Zn/C targets. Transmission electron microscopy showed that ZnO/DLC films were obtainable by using both methods, but only in situ oxidized ZnO/DLC films showed the ultraviolet absorption at ˜370 nm. In situ oxidized films are highly sp3-bonded and rougher than as-deposited films, but as-deposited films are mechanically harder, stiffer, and have higher adhesion strength than in situ oxidized films. X-ray photoelectron spectroscopy revealed that a lower fraction of SiC, but a higher fraction of sp3 bonding was formed in the in situ oxidized ZnO/DLC. This hinted that the presence of oxygen might have scattered the plume’s expansion and reduced the energy possessed by the ions, thus reducing the graphitization and the formation of SiC in DLC matrix. Hence, by altering the deposition mechanism during laser ablation, ZnO/DLC films with modified material properties can be tailored.

A Model for Silicon Dendrite Growth During Laser/Plasma Deposition from a Silane Discharge

1986 ◽  
Vol 75 ◽  
Author(s):  
Harold M. Anderson ◽  
Philip J. Hargis
Keyword(s):  
Laser Plasma ◽  
Plasma Deposition ◽  
Dendritic Structure ◽  
Negative Temperature ◽  
Supercooled Liquid ◽  
Interface Temperature ◽  
Laser Fluences ◽  
Krf Laser ◽  
Si Films ◽  
Tip Radius

AbstractA model for dendrite growths in polycrystalline Si films formed during laser/plasma deposition with a silane discharge and a pulsed KrF laser has been developed. The model assumes a thin (less than 10 nm) amorphous silicon (a-Si) film is deposited on a substrate prior to phase transformation due to laser heating. The observed dendritic structure of the overall polycrystalline Si films is attributed to Si crystals shooting from an excessively supercooled Si liquid bath. Supercooled liquid forms since the melting point for a-Si can be reached at relatively low KrF laser fluences. Latent heat evolved at the solid-liquid interface induces an interface temperature higher than that of the melt and the requisite negative temperature gradient for absolute bath supercooling. Since the formation of an undercooled liquid by fast melting a-Si is also an important first step in explosive crystal regrowth studies, these results may have important implications for crystal growth and transient annealing. A conical approximation model is used in this study to characterize the stability of the dendrite tip in terms of local temperature gradients, i.e., the degree of undercooling at the tip of the parabolic dendrite. The degree of undercooling and hence the tip radius appears to be significantly affected by small changes in the laser fluence. Stability criteria lead to a relationship between regrowth velocity, V, and the tip radius, R, of the form VR2= constant. The size and stability of the dendrite tip is determined from a balance between the destabilizing force due to thermal diffusion and the stabilizing capillary force. Based on the observed tip radii formed at laser fluences from 0.13 to 0.25 J/cm2, the model predicts regrowth velocities in a range between 2.0 and 20 m/s – values consistent with transient annealing studies of a-Si

Aging of Plasma-Deposited Films Prepared from Organic Monomers

2007 ◽  
Vol 4 (S1) ◽  
pp. S784-S789 ◽  
Author(s):  
Sufal Swaraj ◽  
Umut Oran ◽  
Andreas Lippitz ◽  
Jörg F. Friedrich ◽  
Wolfgang E. S. Unger
Keyword(s):  
Plasma Deposited Films ◽  
Deposited Films

Growth Mechanism and Film Properties in Pulsed Laser-Plasma Deposition

1991 ◽  
Vol 236 ◽  
Author(s):  
S. Metev ◽  
K. Meteva
Keyword(s):  
Laser Plasma ◽  
Growth Process ◽  
Plasma Deposition ◽  
Pulsed Laser ◽  
Deposition Process ◽  
Experimental Investigations ◽  
Direct Relation ◽  
Film Properties ◽  
Experimental Conditions ◽  
Laser Flux

AbstractIn the paper the results of a theoretical investigation of the growth process of laser-plasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density, substrate temperature) and film properties (thickness, structure). The results of some experimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical model.

Treatment of vulvar and vaginal dysplasia: plasma energy ablation versus carbon dioxide laser ablation

2021 ◽  
pp. ijgc-2021-002913
Author(s):  
Anna Beavis ◽  
Omar Najjar ◽  
Tricia Murdock ◽  
Ashley Abing ◽  
Amanda Fader ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Laser Ablation ◽  
Carbon Dioxide Laser ◽  
Group Versus ◽  
Demographic Factors ◽  
Cox Proportional Hazards ◽  
Complication Rates ◽  
Recurrence Rates ◽  
Plasma Energy ◽  
Plasma Ablation

ObjectivePlasma energy ablation vaporizes tissues similar to carbon dioxide laser ablation, but is not hindered by the unique hazards and regulation of laser technology. We aimed to evaluate the complication rate and effectiveness of plasma versus laser ablation in the treatment of vulvovaginal high-grade squamous intra-epithelial lesions (HSIL).MethodsWe performed a retrospective cohort study of women treated with plasma or carbon dioxide laser ablation for histologically proven HSIL of the vulva or vagina from January 2014 to October 2019 at a single institution. Demographic factors, surgical characteristics, and complications were compared by ablation type using Fisher’s exact tests. Recurrence-free survival was evaluated by ablation type using Kaplan–Meier curves, weighted log-rank tests, and Cox proportional hazards ratio estimates.ResultsForty-two women were included; 50% underwent plasma and 50% underwent carbon dioxide laser ablation. Demographic factors were similar between the groups. 50% (n=21) were immunosuppressed, 45.2% (n=19) had prior vulvovaginal HSIL treatment, and 35.7% (n=15) were current smokers. Most women (n=25, 59.5%) were treated for vulvar HSIL, 38.1% (n=16) for vaginal HSIL. Complication rates did not differ by treatment: 9.5% (n=2) for laser ablation versus 4.8% (n=1) for plasma ablation (p=1.0). Over a median follow-up time of 29.3 months (IQR 11.0–45.0 months), recurrence rates were similar: 28.6% in the laser ablation group versus 33.3% in the plasma ablation group (weighted log rank p=0.43; 24-month HR 0.54, 95% CI 0.15 to 2.01).ConclusionPlasma energy ablation of vulvovaginal HSIL has similar complication rates and recurrence risk to carbon dioxide laser ablation. This technique could be considered as an alternative treatment modality for vulvovaginal HSIL and warrants further investigation.

Synthesis technique of diamondlike carbon films by laser ablation ion source in atmosphere

1992 ◽  
Author(s):  
Kaoru Suzuki ◽  
Tetsuya Taniyama ◽  
Junji Nakata ◽  
Takaya Masutani
Keyword(s):  
Laser Ablation ◽  
Carbon Films ◽  
Ion Source ◽  
Synthesis Technique ◽  
Diamondlike Carbon

scholarly journals Laser-Plasma Deposition of Silicon Carbonitride Films by the HMDS Vapor Gas Flow Activation after a Laser Beam Focus

2021 ◽  
Vol 11 (07) ◽  
pp. 121-130
Author(s):  
V. N. Demin ◽  
V. O. Borisov ◽  
G. N. Grachev ◽  
A. L. Smirnov ◽  
M. N. Khomyakov ◽  
...  
Keyword(s):  
Laser Beam ◽  
Laser Plasma ◽  
Gas Flow ◽  
Plasma Deposition ◽  
Silicon Carbonitride ◽  
Flow Activation
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