High Frequency Glow Discharge Research Articles

The structure of a-Si:H by small angle x-ray scattering

We use small angle x-ray scattering (SAXS) and density measurements by flotation to examine the microstructure of a-Si:H deposited by various techniques. The systems studied include rf glow discharge (GD) films deposited at different substrate temperatures and a-Si:H deposited using other techniques such as very high frequency GD (VHF GD), sputtering (SP) and hot wire assisted chemical vapor deposition (HW). We review the methodology used to analyze the SAXS data and present extensive data where the SAXS samples were tilted with respect to the x-ray beam axis to examine more closely the microvoid shapes. The present results suggest that the microvoid shapes may be deposition system dependent.

Highly Conductive Microcrystalline Silicon Layers for Tunnel Junctions in Stacked Amorphous Silicon based Solar Cells.

ABSTRACTWe have investigated the influence of substrate temperature on the optoelectronic and structural properties of heavily doped μc-Si:H, prepared with the Very High Frequency Glow Discharge process. At substrate temperatures as low as 160°C we obtain, for films with 0.5μm thickness, maximum conductivities of 100 S/cm and 20 S/cm for <n> and <p> material, respectively. Starting from these values the deposition parameters were optimised for ultrathin layers having thicknesses in the range of 100 to 500Å. We observe that boron doping plays a critical role in the crystallisation of ultrathin films. The thinnest layers investigated so far show conductivities of 0.2 S/cm at d=100Å for <n>, and 0.2 S/cm at d=250Å for <p> material. These properties make μc-Si:H films attractive candidates to form tunnel junctions in tandem solar cells.

Investigation of the high-frequency glow discharge in Ar at 13.56 MHz by spatiotemporal optical emission spectroscopy

The radio frequency glow discharge in Ar at 13.56 MHz has been investigated by using time- and space-resolved emission spectroscopy with a resolution of 0.2 ns. The relative net excitation rate is also obtained by deconvoluting the emission profile considering the effect of the lifetime. From these results, the authors are able to guess the electron transport and the temporal structure of the discharge. ArI(3p5 to 1s4), ArI(2p2 to 1s5) and ArII(4p4D7/2 to 4s4P5/2) lines are selected for observation. The electrons with low energy, epsilon >14.57 eV, are transported corresponding to the phase of the current. The electrons with higher energy, M>35.05 eV, are observed at the phase corresponding to the applied voltage only when the aluminium electrode is used under the present experimental conditions. It is confirmed that the high-energy electrons are secondary electrons emitted from the electrode. The RF discharge in Ar at 13.56 MHz has two modes with a hysteresis loop as the function of input energy.

Thermoluminescence of a polyethylene surface after plasma treatment with a high-frequency glow discharge

The plasma treatment of polyethylene (PE) gives a specific pattern of thermoluminescence (TL). The qualitative difference between the TL curves of PE after plasma treatment and the curves for radioluminescence appears to be due both to specific features of the plasma treatment (attack on the surface of the sample and the unavoidable effect of photobleaching) and to the particular structure of the surface of the polymer (the existence or formation in the surface layer of special low-molecular structures). TL after plasma treatment can therefore be used to investigate the surface structure of polymers.

Population of the excited Ne atoms in 3d levels by dissociative recombination in the neon afterglow plasmas at room temperature

The paper deals with the optical investigation of the dissociative recombination of Ne 2 + molecular ions with electrons in the afterglow period of d.c. and high-frequency glow discharges. It has been confirmed experimentally that the dissociative recombination produces excited atoms in the Ne (3p i ) states and in the Ne (3d j states at room electron temperature. Then, the normalized partial recombination coefficients have been determined as 〈α(3d)〉=0·26 and t<α(3p)〉=0·74.

High rate deposition of a-Si:H films for optoelectronic detectors by VHF-GD

Optoelectronic properties of a-Si:H Shottky barrier photodetectors grown by the VHF-GD process (Very High Frequency Glow Discharge) at a rate of 20 Å/s are presented. The high deposition rate permits the fabrication of thick low cost a-Si:H layers. The thickness of the intrinsic a-Si:H layer was varied from 0.4 μm to 9 μm for light detection between 400 nm and 700 nm. The authors show that the devices have comparable properties to conventional GD-thin-film detectors even if deposited at high rates. Typically, a photovoltaic gain of 10 6 at 650 nm (1 mW/cm 2) and a rise-time of 1 μs were measured for a 5 μm thick detector.

Origin of Boron Contamination of the Intrinsic Amorphous Silicon Hydrogen Alloys in Glow Discharge System

Boron contamination of the intrinsic amorphous silicon hydrogen alloys deposited in a single chamber system using both low (29 kHz) and high (10 MHz) frequency glow discharge has been studied in detail. The contamination process was simulated by flowing the p‐type deposition gas through the system with or without turning on the plasma. Several methods were applied to reduce the contamination and their effects were investigated by measuring the change of the light conductivity and the activation energy of the contaminated i layer. A model that emphasizes the role of plasma in the contamination processes was proposed to explain the observed results. It was found that when using low frequency plasma deposition a dummy cathode method and “soft” deposition of a thin a‐Si:H can be applied to reduce the boron contamination problem.

Preparation and Characterization of Highly Conductive (100 S/cm) Phosphorus Doped νc-Si:H Films Deposited Using the VHF-GD Technique

AbstractWe report on the preparation and characterization of phosphorus doped gc-Si:H films produced by the very high frequency glow discharge (VHF-GD) at a plasma excitation frequency of 70 MHz. We present a systematic study of the deposition parameters i.e. hydrogen dilution of silane, VHF power density, gas phase doping ratio and deposition temperature and their influences on the electrical and structural properties of the material. In contrast to 13.56 MHz GD the VHF plasma conditions favour microcrystalline formation at low power densities; the resulting conductivities are significantly higher than those obtained at 13.56 MHz.

Porometric and electron-microscope investigation of polycaproamide fibres treated with a glow discharge

Morphological changes in polycaproamide fibre which take place on contact with high-frequency glow discharges have been studied.

Introductory Remarks : Fundamental Properties and Internal Structure of Processing Plasma

A variety of plasma processes are summarized from the point of view of discharge physics. Since low temperature plasmas are widely used, our attention is paid to glow discharge, especially high frequency glow discharge. The basic properties and internal structure are discussed.

Stability of a high-frequency glow discharge in the normal combustion regime

A high frequency glow discharge in its high current form differs from a dc discharge in that there is a significant decrease in the role of the pre-anode region in plasma generation [1], thus leading to greater stability [2]. In a dc discharge the pre-anode current-voltage characteristic (CVC) is falling [3], which causes electrodynamic instability of the plasma column and leads to its contraction over times much shorter than the thermal times [4]. It is characteristic that conductivity in the volume of a dc discharge at moderate pressures is caused by drift of ions from the pre-anode region. In an hf discharge the plasma distribution is symmetric about the midpoint of the interelectrode gap and the space charge zones near the electrodes are separated from the volume by narrow zones with high conductivity. Under such conditions, together with volume ionization processes a noticeable contribution to maintenance of conductivity can be produced by ambipolar diffusion and plasma drift due to disruption of quasineutrality [5, 6]. In order to study the stability of an hf discharge plasma column it is of interest to find the current-voltage characteristic of this part of the discharge under conditions of high longitudinal inhomogeneity and low values of E/p. In connection with the experimentally observed weak current form of the discharge [1, 2], which is characterized by a unique value of the normal current density and lacks a proper theoretical explanation, there has been increased interest in the properties of the hf discharge which are produced by phenomena in the pre-electrode regions. In particular, it is necessary to theoretically confirm the similar properties of the dc discharge and the hf discharge in the normal current density regime. The present study will present results of a numerical calculation of an hf discharge in nitrogen with consideration of space charge effects within the framework of a two-dimensional model and calculated the CVC of a plasma column with the diffusion-drift mechanism for maintenance of conductivity.

Coating with silicon carbide in high-frequency discharge

The authors investigate the kinetics of pyrolysis of methyl trichlorosilane and the subsequent chemical vapor deposition and epitaxial growth of silicon carbide on tungsten under the influence of a high-frequency glow discharge. They also assess the diffusional behavior of silicon and carbon in tungsten as a function of temperature and activation energy.

Studies on the Decomposition of NH3 Gas by High Frequency Glow Discharge. II.

Studies on the Decomposition of NH3 Gas by High Frequency Glow Discharge. II.

Studies on the Decompositions of H2O by High Frequency Glow Discharge. I.

Studies on the Decompositions of H2O by High Frequency Glow Discharge. I.

Studies on the Decompositions of H20 by high Frequency Glow Discharge. II.

Studies on the Decompositions of H20 by high Frequency Glow Discharge. II.

Studies on the Decomposition of NH3 Gas by High Frequency Glow Discharge.

Studies on the Decomposition of NH3 Gas by High Frequency Glow Discharge.

On the Characteristics of High Frequency Glow Discharge in Air of Low Pressure

On the Characteristics of High Frequency Glow Discharge in Air of Low Pressure

A note on spectral intensity changes in high-frequency glow discharge in air

A note on spectral intensity changes in high-frequency glow discharge in air

Line Intensity Variations in the Hydrogen High Frequency Glow Discharge

Line Intensity Variations in the Hydrogen High Frequency Glow Discharge

The dissociation of nitrous oxide in the high frequency glow discharge

The dissociation of nitrous oxide in the high frequency glow discharge