Breakdown, scaling and volt–ampere characteristics of low current micro-discharges

Petrović, Zoran Lj.; Škoro, Nikola; Marić, Dragana; Mahony, C. M. O.; Maguire, Paul; Radmilović-Rađenović, M; Malović, Gordana

doi:10.1088/0022-3727/41/19/194002

Cited by 71 publications

(59 citation statements)

References 25 publications

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“…Paschen curve, should be the same for all electrode gaps unless processes that void scaling take place. In micro-discharges, apart from well known processes that cause violation of scaling (gas and electrode heating, stepwise processes and three-body collisions at high pressures), one may expect processes such as field emission and quantum tunnelling of electrons [24]. .…”

Section: Properties Of Micrometer Size Discharges -Scaling Lawsmentioning

confidence: 99%

“…to take into account effective area covered by the discharge, which may be considerably smaller than the area defined by the electrode diameter [25]. Micro-discharges operate at pressures higher than pressures used in standard size discharges, so that the occurrence of constriction in micro-discharge is even more pronounced [24]. Therefore, it is essential to record radial profiles of emission.…”

Section: Properties Of Micrometer Size Discharges -Scaling Lawsmentioning

confidence: 99%

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Breakdown and discharge regimes in standard and micrometer size dc discharges

Škoro¹

2012

J. Phys.: Conf. Ser.

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Breakdown and discharge regimes in standard and micrometer size dc discharges Abstract. In this paper, an overview of our recent experimental studies of the breakdown and operation of non-equilibrium discharges in centimetre and micrometer size geometries is presented. In the centimetre size geometries, we focused on elementary processes and phenomenology in gases used for some of the currently most attractive applications of low temperature plasmas -fluorocarbon gases (CF 4 , CHClF 2 ) and water vapour. Measurements were performed at electrode separation d = 1.1 cm, in a pressure range from 0.1 to 5 Torr. In the case of micro-discharges, the emphasis was on testing the validity of standard scaling laws and proper determination of scaling parameters pd and j/p 2 . This was done at electrode gaps of 200 and 500 μm and pressures of 50 and 20 Torr in argon. The investigation is based on measurements of breakdown potentials (Paschen curves) and Volt-Ampere characteristics, supported by simultaneous ICCD imaging of the discharges. IntroductionOwing to many unique properties, low temperature non-equilibrium discharges have been used in a large number of applications. Fundamental investigations lead to new applications but, recently, in many cases, the needs of applications led to numerous fundamental results. On all accounts, the complexity of these discharges call for full understanding of discharge processes in order to make efficient and reliable devices. Moreover, along with numerous non-equilibrium discharge sources in centimetre size [1,2], many sources with micrometre characteristic dimensions have been introduced recently [3,4]. Hence, an ongoing direction of research about discharges in molecular gases and gas mixtures of interest for applications [5] has been appended with new challenges of discharges taking place between electrodes separated by few tens or hundreds of micrometers -micro-discharges [6]. Additionally, a new type of non-equilibrium discharges taking place in or near liquids has emerged [7], bringing new possibilities for applications together with a whole new set of issues to resolve.Accordingly, results presented in this paper are divided in two sections. The first one deals with measurements conducted with cm-size chamber. Using previously gathered experience on standard size non-equilibrium discharges in rare gases at low pressures [8][9][10][11][12], our research is continued with experimental measurements in gases of interest for applications: fluorocarbons (CF 4 and CHClF 2 ) which are widely used for plasma etching (e.g. [13]) and water vapour that is present as working environment of numerous commercial devices [14]. Measurements in these gases aim to provide reliable and systematic data sets required for plasma models that may be extended to applications involving those gases.

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Section: Properties Of Micrometer Size Discharges -Scaling Lawsmentioning

confidence: 99%

Section: Properties Of Micrometer Size Discharges -Scaling Lawsmentioning

confidence: 99%

Breakdown and discharge regimes in standard and micrometer size dc discharges

Škoro¹

2012

J. Phys.: Conf. Ser.

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“…Charge neutrality and discharge structure are relatively unchanged down to gaps of ∼100 µm [31,32]. We have investigated the dc breakdown and current characteristics of various PP structures and have tested pd and j/p 2 scaling for gaps of a few millimetres down to 20 µm [12,13,33]. Low pressure conventional hollow cathodes (CHCs) have a complicated dependence on various discharge parameters and have been extensively studied [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Characterization of hollow cathode and parallel plate microplasmas: scaling and breakdown

Greenan

Mahony

Mariotti

et al. 2011

Plasma Sources Sci. Technol.

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We present an experimental comparison of parallel plate and hollow cathode microplasma structures, operated at high pressure with narrow anode-cathode gaps. A moveable anode arrangement with ±12 µm spatial resolution was used to vary the electrode separation to cover the pd range between 0.01 and 4 Torr cm for both structures. The hollow cathode discharge was operated with pressure-diameter (pD) product values between 1.8 and 7.2 Torr cm and an aspect ratio of ∼5. Analysis of V -I characteristics shows j/p 2 and j 2 p scaling for low and high current modes, respectively. Electron temperature estimates between 2 and 3 eV were obtained by solving a numerical collisional-radiative model based on transitions from 4p argon levels. The hollow cathode sheath thickness for both ionizing and non-ionizing sheath conditions was determined analytically and the diffusion equation was solved numerically to estimate the plasma density profile for the ionizing sheath case.

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“…At ( pd ) < ( pd ) min , however, we are restricted because the SEE investigations are required for a detailed study in the breakdown regime at lower pressures (see Refs. for details). If ( pd ) < ( pd ) min occurs, the breakdown corresponds to the higher applied voltage.…”

Section: Resultsmentioning

confidence: 99%

“…They concluded that the strong DC fields give notable supports for both the ion current toward the cathode and the development of the electron‐induced ionization. In the low‐current microplasmas, Petrović et al determined the behavior of the Paschen curves with pd and j / p 2 scaling ( d is discharge gap and j is current density) in the range of micrometer scales when only the electrons emitted by the surface with bombardment process are important. However, it can be observed for effects of photons that the γ levels remarkably approach the high values during the development of the photoionization structure .…”

Section: Introductionmentioning

confidence: 99%

Surface behavior based on ion-induced secondary electron emission from semi-insulating materials in breakdown evolution

Koç

Karaköse

Salamov

2013

Phys. Status Solidi A

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This study focuses on analyses of secondary electron emission (SEE) at semiconductor surfaces when the sufficient conditions of space–time distribution occur. Experimental measurements and calculations with the approach of Townsend coefficients, which include the evaluations of ionization coefficient (α) and SEE coefficient (γ) were performed in high‐ohmic InP, GaAs, and Si semiconductor cathodes with argon and air environments in a wide range of E/N (300–10 000 Td). The direct calculations of γ were carried out to determine the behavior of cold‐semiconductor cathode current in a wide range of microgaps (45–525 μm). Paschen curves are interpreted in the dependence of large pd range on breakdown voltage through γ and α/N. Ion‐induced secondary electrons exhibit the direct behaviors affecting the timescale of breakdown evolution in the vicinity of the Paschen minimum during the natural bombardment process with ions of semiconductor cathodes. Also, when α/N rapidly drops and the excitations of gas atoms densely occupy the gas volume, we determined that the photoelectric effect provides a growth for electron emission from semiconductor surfaces at the breakdown stage at the reduced values of E/N. At all pressures, the emission magnitudes of electrons liberated by semiconductor cathodes into vacuum are found as γInP > γGaAs > γSi in breakdown evolution.

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Breakdown, scaling and volt–ampere characteristics of low current micro-discharges

Cited by 71 publications

References 25 publications

Breakdown and discharge regimes in standard and micrometer size dc discharges

Breakdown and discharge regimes in standard and micrometer size dc discharges

Characterization of hollow cathode and parallel plate microplasmas: scaling and breakdown

Surface behavior based on ion-induced secondary electron emission from semi-insulating materials in breakdown evolution

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