摘要:

The axial electron number density distribution of a plasma produced by a rf surface wave launcher has been found theoretically. The results obtained are expressed in the form of universal curves which are applicable to a wide range of experimental conditions (wave frequency, collision frequency, tube radius). The theory agrees well with the available experimental data.

ISSN:0021-8979    

DOI:10.1063/1.332509

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The formation of KrCl*, KrBr*, and KrF* exciplexes, in electron beam irradiated mixtures of krypton with either CF3Cl, CF3Br, SF6, or CF4, are observed to be formed by two distinct and kinetically resolvable time‐dependent processes. The rate of one process is total electron beam energy (dose per pulse) independent but dependent on the partial pressures of the halogen source. This process is attributed to a reaction between high electronic excited states of krypton and the halogen source. The second process is dependent on the total absorbed electron beam energy per pulse and is shown to be due to ion recombination processes. Specifically, the formation is due to a combination of krypton positive ions and halogen negative ions, the latter being formed by dissociative electron capture by the halogen source. This process produces KrF* in high vibrational levels.

ISSN:0021-8979    

DOI:10.1063/1.332510

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The effect of H2on the breakdown potential and Townsend ionization coefficients for Ne‐A mixtures were measured by the luminous‐flux method. Both argon and hydrogen form Penning mixtures with neon. The breakdown potentials for Ne‐A gas mixtures are determined by the Penning reaction, Nem+A→Ne+e+A+, between metastable neon (Nem) and ground state A atoms. At low H2concentrations (<0.1%) the breakdown potentials and Townsend ionization coefficients are unaffected. At higher H2levels (>0.1%), increase in breakdown potential caused by the lowering of the Townsend ionization coefficients depends upon the value of the product,pd, of the fill pressure ( p) and the electrode separation (d). This is due to (1) lowering of electron average energy which determines Nemdensity, and (2) nonionizing reaction, Nem+H2→H*(n=3)+H+Ne, competing with the Penning reaction between Nemand A atoms.

ISSN:0021-8979    

DOI:10.1063/1.332511

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The effect of small amounts of H2(0.005–1.0%) on the deionization processes in Ne‐A discharges was measured by microwave cavity techniques. At low charged particle densities the deionization of discharges produced in Ne‐A mixtures is determined by the ambipolar diffusion of electrons and molecular argon ions (A+2). The charged particle density in the deionization period following a pulsed discharge decays exponentially with time. For a discharge tube of 7 mm i.d. filled with Ne‐A mixtures at a pressure of  20 Torr, the deionization of the plasma occurs with a time constant of 1.3 ms. The presence of a small amount of H2(0.005%) enhances the deionization process drastically. The charged particle density decreases much more rapidly (time constant of 0.61 ms) than in the pure mixture. A similar increase in the deionization rate was measured in pure A. At low charge particle densities the deionization rate is determined by the ambipolar diffusion of a highly mobile hydrogen ion, possibly H+3, compared to relatively less mobile argon ions.

ISSN:0021-8979    

DOI:10.1063/1.332512

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The role of photodetachment in the initiation of electron avalanches near a positive point electrode was investigated for a discharge gap in which the negative ion flux was controlled by UV irradiation of the cathode. For irradiation of the anode region with light beams up to 500 mW, photodetachment was found to make a negligible contribution to avalanche initiation in SF6and O2at pressures from 50 to 500 kPA (∼0.5 to 5 atm). The conditions under which the role of photodetachment might be observed are discussed, and it is shown that for the conditions considered here the expected dominant electron release mechanism in the gap is through collisional detachment of stable negative ions. Previously reported enhancements in avalanche rates resulting from irradiation of a positive point can be explained as arising from increases in negative ion densities due to attachment of photoelectrons ejected by scattered radiation.

ISSN:0021-8979    

DOI:10.1063/1.332513

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Knowledge of the energy distributions of particles in glow discharges is crucial to the understanding and modeling of plasma reactors used in microelectronic manufacturing. Reaction rates, available product channels, and transport phenomena all depend upon the partitioning of energy in the discharge. Because of the nonequilibrium nature of glow discharges, however, the distribution of energy among different species and among different degrees of freedom cannot be characterized simply by one temperature. The extent to which different temperatures are needed for each degree of freedom and for each species is not known completely. How plasma operating conditions affect these energy distributions is also an unanswered question. We have investigated the temperatures of radicals, ions, and neutrals in CCl4, CCl4/N2(2%), and N2discharges. In the CCl4systems, we probed the CCl rotational and vibrational energy distributions by laser‐induced fluorescence spectroscopy. The rotational distribution always appeared to be thermal but under identical operating conditions was found to be ≊400 K colder than the vibrational distribution. The rotational temperature at any point in the discharge was strongly dependent upon both applied power and surface temperature. Thermal gradients as large as 102K mm−1were observed near electrode surfaces but the bulk plasmas were isothermal. When 2% N2was added to a CCl4discharge, N2second positive emission was observed and used to estimate the N2rotational temperature. The results suggest that emission from molecular actinometers can be used to measure plasma temperatures, providing such measurements are not made in close proximity to surfaces.

ISSN:0021-8979    

DOI:10.1063/1.332514

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The variation of the principal characteristics of the mercury visible triplet self‐reversed lines is studied as a function of radial and temporal profiles of the temperature and of the species densities in high pressure mercury discharges (∼2 and ∼3 atm) operating on 50 Hz ac. An investigation is made into the effect of different theoretical and experimental parameters on the shape of calculated self‐reversed lines. By comparison between experimental and theoretical results an estimation is made of the broadening constants and of the transition probabilities of the lines.

ISSN:0021-8979    

DOI:10.1063/1.332515

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

It has been found that while the highly nonuniform direct current breakdown voltageVsof H2exceeds that of D2, theVsof CH4is substantially lower than that of CD4. The former (direct) and the latter (inverse) isotope effects are discussed, respectively, in connection with differences in the ionization coefficients and electron‐impact‐induced dissociation processes of the isotopic pairs of molecules.

ISSN:0021-8979    

DOI:10.1063/1.332462

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Amorphous silicon films, prepared by planar rf magnetron sputtering, in both hydrogenated and unhydrogenated forms, are found to exhibit three distinct types of microstructure depending on the growth conditions: (a) no resolvable microstructure down to 10 A˚; (b) islands of 50–200 A˚ lateral dimensions separated by a network of lower density; (c) a two level pattern wherein conglomerates of 50–200 A˚ islands form columnar regions of 300–500 A˚ lateral dimensions interspersed by a more pronounced low density network. The argon pressure during growth has the dominant influence on the evolution of the microstructure. Type (a) microstructure is obtained at low (≤ 3 mTorr) argon partial pressure irrespective of rf power level, hydrogen partial pressure, and substrate temperature and type (b) and (c) microstructures are observed at higher argon partial pressures (≥10 mTorr). Increasing rf power and substrate temperature at high argon partial pressures result in an enhancement of the microstructural features. Addition of hydrogen enhances the microstructure at low rf power levels and suppresses the microstructure at high rf power levels.

ISSN:0021-8979    

DOI:10.1063/1.332463

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The method to measure boron profile by using the nuclear reaction10B(n,&agr;)7Li is applied to estimate the diffusivity of boron in the glow‐discharged hydrogenated amorphous–silicon (a–Si:H). It is found that the diffusivity of boron ina–Si:H is much larger than that in crystalline silicon (c–Si). For instance, it is about 2×1016cm2/s at 330 °C and larger than inc–Si by twelve orders of magnitude. The activation energy of the diffusivity is also estimated to be 1.5 eV. These values are nearly equal to those of hydrogen ina–Si:H. The minimum duration, in which the characteristics ofp–i–ntypea–Si:H solar cells may start to change due to this boron diffusion, is roughly estimated using both boron diffusivity and its activation energy.

ISSN:0021-8979    

DOI:10.1063/1.332464

出版商:AIP    

年代:1983

数据来源: AIP