摘要:

The dependence of holographic recording on recording light intensity has been experimentally studied in nonannealed amorphous As2S3films. It has been observed that the threshold of the recording intensity is about 10−5W/cm2for 10.5‐&mgr;m‐thick film and a 1 &mgr;m grating period. A phenomenological model is presented to explain the intensity dependence in the 10−5–10−1W/cm2intensity range. According to this model the observed intensity behavior is caused by photoinduced spatially periodic mechanical stress. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360331

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A self‐consistent data reduction of statistical sets of electron probe currents and Thomson scattering spectra is carried out with the help of the strictly determined curve fitting in the mathematical frame of a new regularization procedure [M. V. Chegotov, J. Phys. D27, 54 (1994)]. Both the stability and high speed of the present procedure enable one to process without averaging every electron probe current characteristic or Thomson spectrum of the statistical set at a practically arbitrary noise level and to obtain not only the averaged electron velocity distribution function (EVDF) but even its standard deviation at every point. An algorithm is described which enables one to establish the highest feasible energy resolution EVDF for the given statistical sets of electron probe currents or scattering spectra. These features make this algorithm rather flexible and convenient in particular for the processing of Langmuir‐probe and Thomson scattering measurements. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360332

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a self‐consistent 1D model of the discharge initiated in an ac plasma display panel cell. The model is based on a two‐moments fluid description of electron and ion transport, coupled with Poisson’s equation, and with a set of kinetic equations characterizing the evolution of the population of excited states leading to UV emission in neon‐xenon mixtures. Results are presented in a 90% neon, 10% xenon gas mixture, for a gap length of 100 &mgr;m and a gas pressure of 560 Torr at ambient temperature. Under the conditions above, and for typical sustaining voltages, the duration of the discharge current pulse predicted by the model is on the order of 10 ns while the UV emission lasts for about 5 &mgr;s. The UV production efficiency in the discharge is about 10% for a Ne‐Xe (90‐10) mixture. Results for other neon‐xenon mixtures are also discussed. The model also shows that a non‐negligible part of the UV production occurs in the transient ‘‘plasma column’’ and not only in the sheath region. Voltage transfer curves and margin obtained with this model are presented and compared with available experimental measurements. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360684

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Excited neutrals and fast ions produced in a 13.56 MHz radio‐frequency discharge in a 90% argon −10% hydrogen gas mixture were investigated, respectively, by spatially and temporally resolved optical emission spectroscopy, and by mass‐resolved measurements of ion kinetic energy distributions at the grounded electrode. The electrical characteristics of the discharge were also measured and comparisons are made with results obtained for discharges in pure H2under comparable conditions. Measurements of Balmer‐alpha (H&agr;) emission show Doppler‐broadened emission that is due to the excitation of fast atomic hydrogen neutrals formed from ion neutralization processes in the discharge. Temporally and spatially resolved emission profiles of the H&agr;radiation from the Ar‐H2mixture are presented for the ‘‘slow’’ component produced predominately by electron‐impact dissociative excitation of H2, and for the ‘‘fast’’ component corresponding to energies much greater than can be derived from dissociative excitation. For the Ar‐H2mixture, the fast component is significantly enhanced relative to the slow component. The measured kinetic‐energy distributions and fluxes of predominant ions in the Ar‐H2mixture, such as H3+, H2+, H+, and ArH+, suggest mechanisms for the formation of fast hydrogen atoms. The interpretation of results indicate that H+and/or H3+, neutralized and backscattered by collision with the powered electrode, are the likely sources of fast hydrogen atoms that produce Doppler‐shifted H&agr;emission in the discharge. There is also evidence at the highest pressures and voltages of ‘‘runaway’’ H+ions formed near the powered electrode, and detected with kinetics energies exceeding 100 eV at the grounded electrode. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360333

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A simple model for ionization of sputtered metals by a high‐density plasma is presented. Experimentally, ion flux fractions of greater than 80% can be obtained by sputtering aluminum into a region of dense plasma (ne∼1012cm−3). Such a process has important applications in the filling of high‐aspect‐ratio features encountered in microelectronics fabrication. Both electron‐impact and Penning ionization mechanisms are considered in this model. Under conditions of low electron density (ne≪1011cm−3), Penning ionization is found to be the dominant ionization path. This is consistent with the accepted ionization mechanism for conventional diode sputtering. When high electron densities are generated, however, electron‐impact ionization plays a significant ionization role. Langmuir probe measurements of the inductively coupled plasma indicate that the electron density lies between 2×1011and 2×1012cm−3. The model, in combination with measured plasma density, is used to calculate ion fractions. Modeled and experimentally measured aluminum ion fractions compare favorably. The effects of chamber dimensions, argon pressure, and sputtered metal density are investigated and shown to be important in optimizing the ionization fraction. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360334

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Continuous and pulsed oxygen plasmas have been created in a helicon diffusion reactor used for the deposition of silicon dioxide films. An energy selective mass spectrometer and a Langmuir probe attached to the wall of the silica‐covered aluminum diffusion chamber below the source have been used to characterize the plasma [ion energy distribution function (IEDF), plasma potential, floating potential, plasma density]. The ion flux can be significantly modified by pulsing the discharge. In the continuous case, the IEDF of the O+2ions escaping from the plasma to the sidewalls of the chamber consists of a single peak at an energy corresponding to the plasma potential in the chamber (≊32 V). In the pulsed case, the IEDF exhibits two additional peaks at high (≊60 eV) and low (≊15 eV) energy as a result of different states of the plasma during the pulse period: three regimes corresponding to the plasma breakdown, steady state, and decay have been observed and characterized. The time decay of the fundamental mode of diffusion in the post‐discharge was measured and calculated (about 1 ms). The breakdown regime is highly dependent on the state of the plasma at the end of the post‐discharge. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360335

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Regular oscillations in the current are predicted in low‐pressure, planar discharges under certain conditions in electronegative gas mixtures in which the attachment rate coefficient is large at low values ofE/P, the ratio of the electric‐field strength to the gas pressure. The frequency of the oscillations is about 10 kHz, and depending on the conditions of pressure, gap spacing, and applied voltage, the current wave form varies from a near‐sinusoidal shape to regularly repeating and well‐separated spikes with a peak current density on the order of or less than 1 mA/cm2. The instability which gives rise to these oscillations is due to attachment, and the oscillations result from alternate phases of space charge buildup and decay. Thus, the current oscillations predicted here in planar discharges are analogous to Trichel pulses, periodic current spikes which are observed in negative point‐plane corona discharges in electronegative gases. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360766

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Multipacting discharge conditions in a parallel geometry are first reconsidered according to the so‐called constant‐ktheory of Gill and von Engel [Proc. R. Soc. London A192, 446 (1948)]. Four dimensionless variables are introduced: two for representing in a normalized form the peak value of the applied voltage and its frequency, two for characterizing the emission of secondary electrons from the electrodes. Numerical solutions of the equations developed by the author in a previous article [J. Appl. Phys.71, 4629 (1992)] show the existence, when the constant‐kpostulate is valid, of a larger than previously known set of possible multipacting resonance modes. The effects on them of the electron phase‐focusing requirements for a stable discharge are outlined. A procedure for determining breakdown voltages of the multipacting discharge through Monte Carlo simulations is then described. A set of simulation results is presented and compared with the corresponding data obtained from the constant‐ktheory: Except for the cutoff frequency values, the agreement is very good for the lowest‐mode breakdown. In the presence of higher modes, breakdown voltages obtained from simulations are higher than the corresponding minimum breakdown values from the constant‐ktheory, but the transitions between successive modes, when the frequency is increased, can generally be recognized. These results confirm also the main features which are found in the plots of the experimental data reported by various authors, and particularly, at the highest frequencies, the linear dependence of the breakdown voltage on the product of frequency times electrode separation. In addition to breakdown voltages, Monte Carlo simulations provide the corresponding distributions of electron crossing times. These distributions prove the existence, under well‐simulated physical conditions, of the breakdown mode first reported in the author’s previous article. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360336

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Room‐temperature photoluminescence measurements are performed in order to study the effect of thermal annealing on phosphorus implanted silicon wafers. Measurements are carried out at near band gap excitation with a Nd:YAG laser operating at 1.06 &mgr;m. Photoluminescence measurements are also carried out with 0.488 &mgr;m laser excitation. It was found that implantation conditions (dose and energy) and annealing temperature strongly influence the intensity of the photoluminescence signal. Contribution from the bulk silicon and the effects from the ion implantation to the photoluminescence signal are discussed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360337

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Edge‐defined film‐fed‐growth (EFG) Si is investigated using deep‐level transient spectroscopy and surface photovoltage. An impurity energy level of CrB was found at 0.27 eV above the valence band in EFG Si contaminated with Cr. The Cr diffusion coefficient in EFG Si was obtained as 2×10−17cm2/s at room temperature using association and dissociation of CrB pairs after a 210 °C dissociation anneal. Most of the deep‐level transient spectroscopy (DLTS) spectra are not analyzable with conventional methods due to abnormally broad peaks. DLTS spectra of as‐grown EFG Si are modeled using a Gaussian distribution of impurity energy states. The simulated DLTS peaks agree well with measured data explaining the origin of the deep‐level impurities of EFG Si. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360338

出版商:AIP    

年代:1995

数据来源: AIP