摘要:

The broadening and shift of the optically thin Hg 577 and 491.6 nm lines emitted in high‐pressure mercury discharges operating at 50 Hz ac frequency are studied. An investigation is carried out in order to appreciate the influence of different factors on the broadening and shift of the local line profile. Comparison between computed and experimental apparent line shapes permits the determination of a set of broadening and shift parameters which leads to a satisfactory representation of the line shapes. Furthermore, applications to mercury discharge diagnosis are proposed.

ISSN:0021-8979    

DOI:10.1063/1.350664

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Repetitive discharges, powered by a train of negative, flat‐topped maintenance pulses of amplitudeV1, can be suppressed by applying a similarly shaped ‘‘spurious’’ voltage pulse of amplitudeV2at a time interval oftqafter each maintenance pulse. Suppression occurs, even with quite small values ofV2, a phenomenon that can be explained by taking account of how the spurious pulses affect the electric charges left behind in the discharge tube by each of the driven discharges. The results are relevant to elucidating ‘‘cross talk’’ between discharge tubes in display panels.

ISSN:0021-8979    

DOI:10.1063/1.350665

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Self‐consistent fluid and particle‐in‐cell models of radiofrequency glow discharges have been used to analyze the existence of different regimes experimentally observed in silane discharges. The discharge ionization mechanism changes from a situation where the ionization occurs during the expansion of the sheath to a situation where the bulk plasma plays a major role. We suggest that the transition is consistent with powder formation with increasing power. This leads to supplementary losses of electrons and then to an increase in the plasma electric field.

ISSN:0021-8979    

DOI:10.1063/1.350666

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The inductance of an arc discharge has been modeled and a mathematical formula given for the arc inductance in terms of its geometrical dimensions. This formula agrees with the experimental results and is used to determine the arc‐channel radius. Inductance measurements have been taken for various values of pressure, interelectrode distance and applied voltage in a triggered spark gap. The dependence of inductance upon these parameters has been explained through the existing variations of the arc‐channel cross section. Two mechanisms are responsible for the variations of inductance. The first is diffusion and the second is the tendency of the current channel to vary diameter with pressure, interelectrode distance, and applied voltage. The time history of the arc‐channel inductance has been investigated. Finally, the ambipolar diffusion coefficient and the total charge number of the arc channel has been obtained.

ISSN:0021-8979    

DOI:10.1063/1.350667

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Cathode spots on arc‐cleaned copper and molybdenum electrodes in vacuum were studied by fast image converter framing and streak camera photography with high temporal and spatial resolution. The frame exposure time was 20 ns and the interframe period was 200 ns; the streak sweep time was between 200 ns and 1 &mgr;s. Spatial structures with a resolution of 5 &mgr;m could be determined by observing the spot movement with a small slit at the streak camera and a high sweep speed. Strong fluctuations of the light emission of the spot were found with characteristic times of 50–100 ns. When the spot moved out of the slit field of view a stepwise decrease occurred in the measured light, indicating an internal substructure of the spot with distances between fragments less than 10 &mgr;m and even smaller fragment diameters. The current per fragment was estimated to be 20–40 A. The frames confirm the short time constants of the spot. From frame to frame a spot motion was observed in most cases, yielding spot residence times <200 ns.

ISSN:0021-8979    

DOI:10.1063/1.350668

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We have measured the initial silane and polysilane product yields from disilane decomposition in rf and dc discharges, at 25 and 250 °C and 20 Pa (0.15 Torr) pressure as typically used fora‐Si:H film deposition. From analyses of these yields we conclude that the initial Si2H6fragmentation pattern is SiH3+SiH2+H (91±9%) and H3SiSiH+2H (9±9%), that the primary product of the H+Si2H6reaction is SiH4+SiH3, and that SiH3is the dominant radical causing film growth. We have measured a radical‐surface reaction probability of 0.34±0.03, very similar to that observed for SiH3in SiH4discharges. We report a spatial distribution of emission indicative of a &ggr;‐regime discharge. From deposition on glass fibers strung between the electrodes, we find that highly straineda‐Si:H film is produced everywhere except on or near the electrodes, suggesting that energetic ion impact is necessary to yield useful films in disilane discharges.

ISSN:0021-8979    

DOI:10.1063/1.350669

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A model of the negative glow of a low‐pressure Hg‐Ar discharge is described. The model contains a number of important physical processes (in particular noble‐gas excitation and multiple‐step ionization) that have not been included in earlier models. The model has also been coupled to a simple description of the Faraday dark space to enable predictions to be made of the axial density and potential profiles across the whole negative‐glow Faraday dark‐space positive‐column region. Results of a number of numerical computations are presented and in general these have been found to be in agreement with experimental observations. The effect of varying the various input parameters to the model on its predictions has also been studied and the results of this will also be presented.

ISSN:0021-8979    

DOI:10.1063/1.350670

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Yb/p‐InP and Au/n‐InP tunnel metal‐insulator‐semiconductor (MIS) diodes were irradiated with 1 MeV electrons to a fluence of 1×1015e−/cm2. The forward current‐voltage (I‐V) and high‐frequency capacitance‐voltage (C‐V) characteristics of electron‐irradiated Yb/p‐InP MIS diodes were measured over the temperature range 80–450 K. From theI‐V/Tdata, the temperature dependence of the ideality factornand the reverse saturation currentI0was determined. The temperature dependence ofI0fit very well to the thermionic emission model over the temperature range 250–450 K. The zero bias, zero temperature barrier height, &fgr;0=0.93±0.04 V, obtained from the above fitting procedure, agreed within experimental error with the value of &fgr;0=0.99±0.05 V, obtained from theC‐V/Tmeasurements. The interface‐state density at the insulator‐semiconductor interface of the irradiated Yb/p‐InP tunnel diodes, deduced from the forward bias dependence ofnat 309.1 K, was three times smaller than the one for the nonirradiated diodes. The deep‐level transient spectroscopy studies in irradiated Yb/p‐InP diodes indicated that the electron irradiation annealed an electron trap, introduced a new hole trap, shifted the other two original hole traps to slightly higher energies, increased their capture cross section by an order of magnitude, and reduced their concentration by about 50%. In Au/n‐InP MIS diodes, electron irradiation annealed one electron trap and created a new electron trap, shifted the other two original electron traps to slightly lower energies, lowered the capture cross sections by an order of magnitude, and increased their concentrations by nearly 50%.

ISSN:0021-8979    

DOI:10.1063/1.350671

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We have used broadband synchrotron radiation to induce selective area surface doping of boron into silicon. The source of the boron wasnido‐decaborane (B10H14) adsorbed on Si(111) at 100 K. Irradiation caused decomposition of the adsorbed molecule which lead to an enhanced concentration of free boron in the irradiated area. Using Si 2pcore level photoelectron spectroscopy, the surface chemical composition and Fermi level position in both the irradiated and unirradiated regions were determined. The downward movement of the Fermi level was greater in the irradiated region than in the unirradiated region, and greater forn‐type than forp‐type Si.

ISSN:0021-8979    

DOI:10.1063/1.350619

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The orientational order induced in a liquid crystal (LC) monolayer of adsorbed 4‐n‐octyl‐4’‐cyanobiphenyl molecules on rubbed substrates is studied by measuring the second‐harmonic response. By systematically varying the rubbing conditions and measuring the induced LC bulk and monolayer alignment, we can conclude that the homogeneity of the LC bulk alignment and the surface in‐plane order parameter of the LC monolayer are closely related. The polar and azimuthal ordering of the LC monolayer, however, are found to be decoupled. By rubbing polyimide films twice and studying other rubbed surfaces, we show that two mechanisms are responsible for the LC alignment, depending on the kind of substrate that is used. For rubbed bare glass substrates long‐range elastic interactions, which do not affect the monolayer alignment, are dominant. In the case of rubbed polyimide films molecular short‐range interactions are responsible for the alignment of both the LC bulk and the LC monolayer.

ISSN:0021-8979    

DOI:10.1063/1.350620

出版商:AIP    

年代:1992

数据来源: AIP