Spot patterns and instabilities in a pulsed low-pressure rf glow discharge

Voronov, M.; Hoffmann, Volker; Steingrobe, Tobias; Büscher, Wolfgang; Engelhard, Mark H.; Storey, Andrew P.; Ray, Steven J.; Hieftje, Gary M.

doi:10.1088/0963-0252/23/5/054009

Cited by 8 publications

(10 citation statements)

References 19 publications

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“…Readings for the center were taken by averaging the intensity values of a 208 pixel area circle on the axis of the plasma. Our results and those by Voronov et al 22 show that an alternative approach to GDOES elemental mapping of large diameter samples is necessary. Forward power began to uctuate at pressures over 1870 Pa, causing a great build-up of heat in the cathode, thus becoming the upper practical pressure limit.…”

Section: Resultssupporting

confidence: 69%

“…3). Voronov et al 22 heterogeneities in the discharge of a GD chamber that could accommodate 80 mm diameter surface samples when operated at pressures required for obtaining laterally resolved information. Readings for the lateral position were taken by averaging the intensity values of a 208 pixel area circle centered 20 mm from the axis of the plasma at 30 degree increments.…”

Section: Resultsmentioning

confidence: 99%

“…19,20 Voronov et al 21 developed a GD source with which they could analyze samples as large as 8 cm diameter, but found that the source had limitation of power density and pressure. 22 Herein, the development of a GD lamp to accommodate large diameter samples is presented. 22 Herein, the development of a GD lamp to accommodate large diameter samples is presented.…”

Section: Introductionmentioning

confidence: 99%

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Glow discharge optical emission spectrometry elemental mapping with restrictive anode array masks

Kroschk

Usala

Addesso

et al. 2016

J. Anal. At. Spectrom.

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Large-area surface elemental mapping is highly beneficial for a multitude of applications in fields from materials science to biology. Current typical methods, however, suffer from long acquisition times. Glow Discharge Optical Emission Spectrometry (GDOES), under pulsed-power and higher pressure operation, exhibits a great potential for ultrahigh throughput chemical imaging of large surface area samples. Up until now, various proof-of-principle studies of GDOES elemental mapping have only been applied to smaller surface area samples. Thus, there is a need for development of GDOES systems that allow for analysis of large area samples. Here, the design of different GD configurations for large area sample (10 cm diameter) analysis is investigated as a function of operating conditions such as pressure (133-4000 Pa), applied power (up to 5 kW), and pulsing. An open face electrode (OFE) design generatedundesirable heterogeneous plasma at the higher pressures required for achieving spatial resolution. On the other hand, a restrictive anode array mask (RAAM) design provided notable homogeneity within the same pressure range and enabled the lateral resolution of 1 mm diameter silver inclusions embedded in copper. RAAMS were designed varying thickness (3 mm and 12 mm), aperture size (4, 6, 8 mm), geometry, and grounding. Also, as the section sputtered is restricted to the area covered by the apertures, the RAAM provides the opportunity for subsequent analysis of the unsputtered regions via alternative methods. In addition, the RAAM permits higher power densities to be achieved within the limitations of the power supply. These findings help to pave the way for exploiting the full potential of GDOES and its ultrahigh throughput elemental mapping of large surface area samples.

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Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Glow discharge optical emission spectrometry elemental mapping with restrictive anode array masks

Kroschk

Usala

Addesso

et al. 2016

J. Anal. At. Spectrom.

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“…Stationary and rotating spot patterns have been observed in a pulsed rf discharge [164]. Well-defined rotating regions of high plasma emissivity and ionization (so-called spokes) forming symmetric patterns have been observed in high-power impulse magnetron sputtering; e.g.…”

Section: Observations Of Spots and Patterns On Electrodes Of Gas Discmentioning

confidence: 99%

Multiple solutions in the theory of dc glow discharges and cathodic part of arc discharges. Application of these solutions to the modeling of cathode spots and patterns: a review

Benilov

2014

Plasma Sources Sci. Technol.

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A new class of stationary solutions in the theory of glow discharges and plasma-cathode interaction in ambient-gas arc discharges has been found over the past 15 years. These solutions exist simultaneously with the solution given in textbooks, which describes a discharge mode with a uniform or smooth distribution of current over the cathode surface, and describes modes with various configurations of cathode spots: normal spots on glow cathodes, patterns of multiple spots recently observed on cathodes of glow microdischarges and spots on arc cathodes. In particular, these solutions show that cathode spots represent a manifestation of self-organization caused by basic mechanisms of the near-cathode space-charge sheath; another illustration of the richness of the gas discharge science. As far as arc cathodes are concerned, the new solutions have proved relevant for industrial applications. This work is dedicated to reviewing the multiple solutions obtained to date, their systematization, and analysis of their properties and physical meaning. The treatment is performed in the context of general trends of self-organization in bistable nonlinear dissipative systems, which allows one to consider glow discharges or arc-cathode interaction within a single physically transparent framework without going into mathematical details and offers a possibility of systematic computation of the multiple solutions. Relevant computational aspects and experimental data are discussed.

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“…Several aspects of depth-profile GD analysis can limit precision and accuracy. Instrumental conditions can play a role if redeposition occurs, 25 electric fields are uneven, 26 or conditions in the discharge change 26 . Interfacial effects can also be important if the transition between layers is large enough.…”

Section: Introductionmentioning

confidence: 99%

Emergence and consequences of lateral sample heterogeneity in glow discharge spectrometry

Storey

Ray

Hoffmann

et al. 2016

Spectrochimica Acta Part B: Atomic Spectroscopy

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Conventional glow discharge emission or mass spectrometry requires the assumption that the surface of the sample is homogeneous. However, recent developments in glow discharge imaging appear to offer an opportunity to obtain three-dimensional concentration maps, in which this assumption is no longer necessary. Here, experiments, models, and a summary of earlier work are combined to examine the sputtering behavior of elemental and morphological heterogeneities in a sample. The theoretical model reveals gaps in current knowledge of glow discharge sputtering of heterogeneous samples, particularly indicating that heterogeneity in the sample leads to roughened crater bottoms and how additional morphology can evolve. Additionally, a three-dimensional profiling microscope is used to characterize the effects of surface inclusions on the sputtering process in a DC glow discharge in a reduced-pressure argon environment. Findings have important implications for bulk analysis, depthprofiling, and elemental surface mapping with glow discharge spectrometry.

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Spot patterns and instabilities in a pulsed low-pressure rf glow discharge

Cited by 8 publications

References 19 publications

Glow discharge optical emission spectrometry elemental mapping with restrictive anode array masks

Glow discharge optical emission spectrometry elemental mapping with restrictive anode array masks

Multiple solutions in the theory of dc glow discharges and cathodic part of arc discharges. Application of these solutions to the modeling of cathode spots and patterns: a review

Emergence and consequences of lateral sample heterogeneity in glow discharge spectrometry

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