Optical absorption spectroscopy study of the role of plasma chemistry in YBa2Cu3O7 pulsed laser deposition

Sakeek, H. F.; Morrow, Thomas; Graham, W. G.; Walmsley, D.G.

doi:10.1063/1.105628

Cited by 44 publications

(14 citation statements)

References 14 publications

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“…They showed the effects of the jet formation and of the segregation of heavy and light components. However, the effects of many other processes, such as the formation of ions and chemical reactions, can also influence the properties of gas flow, 25 and were not considered in a Monte Carlo simulation of laser desorption.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation study of the effects of nonequilibrium chemical reactions during pulsed laser desorption

Itina

Tokarev

Marine

et al. 1997

The Journal of Chemical Physics

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Monte Carlo simulation is used to study the role of chemical reactions in the gas flow of particles laser desorbed from the target into a vacuum. The influence of recombination and dissociation processes on the properties of the gas flow is considered. It was found that chemical reactions have a significant effect on the composition of the desorption jet and on the angular and mean energy distributions of the desorbed particles. The study of these phenomena is of a particular interest for the understanding of the process of thin film deposition by pulsed laser ablation.

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Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation study of the effects of nonequilibrium chemical reactions during pulsed laser desorption

Itina

Tokarev

Marine

et al. 1997

The Journal of Chemical Physics

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“…These are dominant in the plume. Previously [3] we have demonstrated by absorption spectroscopy that some molecular material is initially ejected and additional oxidation occurs at the plume-oxygen interface. Fast prompt species were seen to initiate the chemical activity at the interface, and the processes were subsequently sustained by slower, more numerous species evaporated from the target surface.…”

Section: Resultsmentioning

confidence: 98%

“…Detection was with a fast (EMI 6097) photomultiplier and Boxcar averager. For absorption studies the plume was backlighted by flashlamp radiation (5 7/~s pulse duration) [3].…”

Section: Methodsmentioning

confidence: 99%

Absorption and emission spectra of the YBCO laser plume

Morrow¹,

Sakeek²,

Astal³

et al. 1994

J Supercond

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The plasma produced during laser ablation deposition of thin film YBCO has been studied by optical emission spectroscopy. There is evidence of increased YO band emission in the range 590-625 nm as the ambient oxygen gas pressure confining the plume is increased in the range 30-200 m Torr. Temporal profiles show that close to the target the plume is insensitive to ambient oxygen pressure. It is deduced that the optical emission here is excited by electron impact excitation. Further away from the target there is evidence that two distinct processes are at work. One is again electron excitation; the emission from this process decreases with distance because the expanding plmne cools and collisions become less frequent in the expanding gas. The second is driven by oxidation of atomic species expelled at high speeds from the target. The main region of this activity is in the plume sheath where a shock front ensures heating of ambient O2 and reaction of monatomic plasma species to form oxide in an exotherrnic reaction. Spatial mapping of the emission demonstrates clearly how increasing oxygen gas pressure confines the plasma and enhances the emission intensity from the molecular YO species ejected from the target in a smaller region close to the target. Ba + is observed as a dominant species only very close to (within 1 mm of) the target. Absorption spectra have been taken in an attempt to examine ground state and cool species in the plume. They reveal the quite surprising result that YO persists in the chamber for periods up to 1 msec. This suggests an explanation for the recent report of off-axis laser deposition in terms of simple condensation. Previously, quasi-ballistic transfer of material from target to substrate has been considered the only significant process.

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“…[74,75] Plume stoichiometry has also been studied with the goal of determining whether deposited films are formed directly from ablated particles or from condensation of atoms and molecules on the deposition surface. There is disagreement in the literature with some authors asserting that oxides are a nascent ablation product, [39] while others suggest oxides are formed by a more complex mechanism by the reaction of Y + O 2 → YO* + O, with the subsequent YO* → YO explaining the strong YO emission band.…”

Section: Pulsed Laser Deposition Diagnosticsmentioning

confidence: 99%

Electronic State Distributions of YBa₂Cu₃O_7-x Laser-Ablated Plumes

Kee

Perram

2010

Appl Spectrosc

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The application of spectral and imagery diagnostics to YBa 2 Cu 3 O 7 (YBCO) laser-ablated plumes was systematically studied to determine their effectiveness for process control. Emission signatures were collected for plumes created by ablating bulk YBCO with a pulsed laser source. A KrF (λ=248 nm) laser source operating at 4-10 J/cm 2 at a 4-10 Hz pulse repetition frequency was used to ablate a bulk YBCO target at O 2 background pressures ranging from 50 to 400 mTorr. Emission spectra were collected over the 500 to 860 nm bandpass at distances from the target ranging from 31.4 to 55.0 mm. Of 87 observed emission lines, 76 were assigned to specific transitions with the aid of calibration lamps and reference to tables of energy levels. Line fluences were corrected for self-absorption, and electronic state distributions were calculated using the most recent NIST transition probabilities.

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Optical absorption spectroscopy study of the role of plasma chemistry in YBa2Cu3O7 pulsed laser deposition

Cited by 44 publications

References 14 publications

Monte Carlo simulation study of the effects of nonequilibrium chemical reactions during pulsed laser desorption

Monte Carlo simulation study of the effects of nonequilibrium chemical reactions during pulsed laser desorption

Absorption and emission spectra of the YBCO laser plume

Electronic State Distributions of YBa₂Cu₃O_7-x Laser-Ablated Plumes

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Optical absorption spectroscopy study of the role of plasma chemistry in YBa2Cu3O7 pulsed laser deposition

Cited by 44 publications

References 14 publications

Monte Carlo simulation study of the effects of nonequilibrium chemical reactions during pulsed laser desorption

Monte Carlo simulation study of the effects of nonequilibrium chemical reactions during pulsed laser desorption

Absorption and emission spectra of the YBCO laser plume

Electronic State Distributions of YBa2Cu3O7-x Laser-Ablated Plumes

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Product

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Electronic State Distributions of YBa₂Cu₃O_7-x Laser-Ablated Plumes