A tuned Langmuir probe for measurements in rf glow discharges

Paranjpe, Ajit; McVittie, J.P.; Self, S. A.

doi:10.1063/1.345109

Cited by 158 publications

(48 citation statements)

References 17 publications

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“…The measurement of electron density can be performed by applying simple or sophisticated probe techniques [22,3,23]. But in our case the probe techniques did not lead to satisfying results because of a destruction of the disc structure by the probe.…”

Section: E L E C T R O N D E N S I T Y M E a S U R E M E N T Smentioning

confidence: 93%

Investigation of an Enhanced Glow Structure in a Low‐Pressure rf Discharge in Helium

Flohr¹,

Schirmer²,

Piel³

1993

Contrib. Plasma Phys.

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Spatially resolved plasma induced emission spectroscopy (PIE) is applied to a symmetric parallel plate discharge in helium under rf excitation at 13.56 MHz. The optical emission features are studied in the pressure range of 10-360 Pa and power densities from 6 mW/cm3 to 90 mW/cm3. At pressures above 60 Pa and power densities exceeding 50 mW/cm3 the transition from the a-to the y-mode is observed, which, in helium, is accompanied by the formation of a disk-shaped brightly luminous glow. A marked difference between the emission from levels of the triplet and singlet system of the helium atom occurs above this threshold of applied power. The spatial emission distribution of equivalent lines of the helium atom is rather different under pressure variation. Therefore the spatial distribution of the metastable levels is concluded to be substantially different between singlets and triplets. This effect is attributed to a rapid decrease of electron temperature and increase of electron density which is a characteristic of the transition between the two heating modes. Low temperature and high density of the electrons favour an overproportional growth of the associated 2 'S destructiqn rate, i.e., singlet to triplet conversion. A similar effect has been reported for a dc discharge by LAWLER et al. [I].

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Section: E L E C T R O N D E N S I T Y M E a S U R E M E N T Smentioning

confidence: 93%

Investigation of an Enhanced Glow Structure in a Low‐Pressure rf Discharge in Helium

Flohr¹,

Schirmer²,

Piel³

1993

Contrib. Plasma Phys.

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“…This energy is calculated by subtracting the substrate bias, V S0 , from the plasma potential with respect to ground, V P0 . A Langmuir probe 11 was used to measure V P0 , the electron temperature T e , and the plasma density N. Values of V P0 Ϸ40 V, T e Ϸ 8 eV and N Ϸ 5ϫ10 16 m Ϫ3 were obtained for an argon flow of 2.8 sccm and a rf power of 300 W. Note that these results are practically unaffected by changing the substrate bias through the tuning circuit. From these values and the Bohm sheath criterion, the ion flux to the substrate may be estimated, 12 and we found i ϭ1.3ϫ10 20 m Ϫ2 s Ϫ1 .…”

Section: 10mentioning

confidence: 97%

Ion assisted deposition of thin films by substrate tuned radio frequency magnetron sputtering

Lousa

Gimeno

1997

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The substrate tuning technique was applied to a radio frequency magnetron sputtering system to obtain a variable substrate bias without an additional source. The dependence of the substrate bias on the value of the external impedance was studied for different values of chamber pressure, gas composition and rf input power. A qualitative explanation of the results is given, based on a simple model, and the role of the stray capacitance is clearly disclosed. Langmuir probe measurements show that this system allows independent control of the ion flux and the ion energy bombarding the growing film. For an argon flow rate of 2.8 sccm and a radio frequency power of 300 W ͑intermediate values of the range studied͒ the ion flux incident on the substrate was 1.3ϫ10 20 m Ϫ2 s Ϫ1 . The maximum ion energy available in these conditions can be varied in the range 30-150 eV. As a practical application of the technique, BN thin films were deposited under different ion bombardment conditions. An ion energy threshold of about 80 eV was found, below which only the hexagonal phase was present in the films, while for higher energies both hexagonal and cubic phase were present. A cubic content of about 60% was found for an ion energy of 120 V.

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“…However, CCP as an independent plasma source for VG synthesis is commonly considered to be insufficient [22] because of the relatively low electron density and electron energy. The plasma density and electron temperature of CCP (Langmuir probe measurements showed that the typical electron density was 10 9 -10 10 , and 10 11 cm −3 for high-frequency CCPs [23,24]) are obviously lower than those of the above mentioned high-density plasma sources (10 10 -10 12 cm −3 for MW and ICP plasmas, and 10 13 cm −3 for helicon plasmas) [18,25]. Meanwhile, the high sheath potential of CCP could possibly destroy the surface bonds and prevent the growth of high quality crystals.…”

Section: Radio Frequency Plasmasmentioning

confidence: 99%

PECVD Synthesis of Vertically-Oriented Graphene: Mechanism and Plasma Sources

Chen

2015

Vertically-Oriented Graphene

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The plasma-enhanced chemical vapor deposition (PECVD) method is a key method for synthesizing vertically-oriented graphene (VG). Because the plasma region provides active species (e.g., energetic electrons, excited molecules and atoms, free radicals, and photons), PECVD offers several advantages in nanostructure synthesis, e.g., a relatively low substrate temperature, a high growth selectivity, and good control in nanostructure ordering/patterning. These features make PECVD the most suitable method for VG growth. On the other hand, the growth of VG using PECVD is a quite complex process due to the complexity of plasma chemistry. The morphology and structure of the VG sheets produced by PECVD are strongly dependent on the types of plasma sources and a series of operating parameters, such as feedstock gas type and composition, the substrate temperature, and the operating pressure. In this chapter, we first discuss the growth mechanism of VG in a PECVD process and then discuss how plasma sources affect the VG growth. Characterization of PECVD-produced VG from various plasma sources using Raman spectroscopy, a powerful tool to study carbon nanostructures, is also discussed in this chapter.

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A tuned Langmuir probe for measurements in rf glow discharges

Cited by 158 publications

References 17 publications

Investigation of an Enhanced Glow Structure in a Low‐Pressure rf Discharge in Helium

Investigation of an Enhanced Glow Structure in a Low‐Pressure rf Discharge in Helium

Ion assisted deposition of thin films by substrate tuned radio frequency magnetron sputtering

PECVD Synthesis of Vertically-Oriented Graphene: Mechanism and Plasma Sources

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