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  • 1
    Electronic Resource
    Electronic Resource
    Dependence of intrinsic stress in hydrogenated amorphous silicon on excitation frequency in a plasma-enhanced chemical vapor deposition process (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3220-3222 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intrinsic stress measurements were carried out on hydrogenated amorphous silicon (a-Si:H) films deposited with different excitation frequencies (13.56–70 MHz), by plasma-enhanced chemical vapor deposition. It was observed that films deposited at 70 MHz have one order of magnitude smaller intrinsic stress than those deposited at 13.56 MHz. These results have been linked to the estimated variation of the ion impact energy as a function of excitation frequency, deduced from the measured variation of the peak-to-peak voltage between the electrodes. The observation of diminished ion energy at higher excitation frequencies has been interpreted as the cause, both of the decrease in intrinsic stress as well as of the measured increase in surface roughness, of films prepared at higher frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351440
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  • 2
    Electronic Resource
    Electronic Resource
    Time-resolved measurements of highly polymerized negative ions in radio frequency silane plasma deposition experiments (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1340-1353 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The time-resolved fluxes of negative polysilicon hydride ions from a power-modulated rf silane plasma have been measured by quadrupole mass spectrometry and modeled using a simple polymerization scheme. Experiments were performed with plasma parameters suitable for high-quality amorphous silicon deposition. Polysilicon hydride anions diffuse from the plasma with low energy (approximately 0.5 eV) during the afterglow after the electron density has decayed and the sheath fields have collapsed. The mass dependence of the temporal behavior of the anion loss flux demonstrates that the plasma composition is influenced by the modulation frequency. The negative species attain much higher masses than the positive or neutral species and anions containing as many as sixteen silicon atoms have been observed, corresponding to the 500 amu limit of the mass spectrometer. This suggests that negative ions could be the precursors to particle formation. Ion–molecule and ion–ion reactions are discussed and a simple negative ion polymerization scheme is proposed which qualitatively reproduces the experimental results. The model shows that the densities of high mass negative ions in the plasma are strongly reduced by modulation frequencies near 1 kHz. Each plasma period is then too short for the polymerization chain to propagate to high masses before the elementary anions are lost in each subsequent afterglow period. This explains why modulation of the rf power can reduce particle contamination. We conclude that for the case of silane rf plasmas, the initiation steps which ultimately lead to particle contamination proceed by negative ion polymerization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356413
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  • 3
    Electronic Resource
    Electronic Resource
    Visible photoluminescence from hydrogenated silicon particles suspended in a silane plasma (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 61-66 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Visible photoluminescence at room temperature has been observed in amorphous hydrogenated silicon particulates during their formation in a silane radio-frequency plasma. Oxygen injection along with mass spectrometry measurements demonstrate that oxygen has no influence on the photoluminescence. The appearance of visible photoluminescence coincides with a particle agglomeration phase as shown by laser light scattering experiments, and electron microscopy shows silicon nanocrystals within these particulates. These observations of visible photoluminescence are consistent with the model of quantum confinement in the silicon nanocrystals. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360582
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  • 4
    Electronic Resource
    Electronic Resource
    Particle agglomeration study in rf silane plasmas: In situ study by polarization-sensitive laser light scattering (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2069-2078 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To determine self-consistently the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering was used. Cross-polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135° and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross-polarization intensities is accompanied by low-frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log-normal particle size distribution. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363118
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  • 5
    Electronic Resource
    Electronic Resource
    Microstructural properties of silicon powder produced in a low pressure silane discharge (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3729-3733 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon powders produced in a low pressure silane plasma show varying structural properties depending on the location of collection of the powders in the reactor. This is revealed by high resolution transmission electron microscopy, infrared and Raman spectroscopy. The particulates are found to consist either of heterogeneously distributed amorphous and crystalline phases or of nanoscale particles with amorphous and molecular like spectral features as found from the Raman spectroscopic studies. Infrared spectra show clustered silicon-hydrogen phases and the presence of oxidized phases in the powder, upon exposure to atmosphere. Phonon confinement effects due to the nanometer size and expansive strain is observed in the vibrational Raman spectra. The average particle size estimated from the observed phonon quantum confinement corresponds with the particle sizes observed by high resolution electron microscopy if strain contributions are included. Annealing at temperatures as low as 300 °C leads to Raman vibrational band similar to crystalline silicon. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358612
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  • 6
    Electronic Resource
    Electronic Resource
    Influences of a high excitation frequency (70 MHz) in the glow discharge technique on the process plasma and the properties of hydrogenated amorphous silicon (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5665-5674 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogenated amorphous silicon has been prepared at a plasma excitation frequency in the very-high-frequency band at 70 MHz with the glow discharge technique at substrate temperatures between 280 and 50 °C. The structural properties have been studied using hydrogen evolution, elastic recoil detection analysis, and infrared spectroscopy. The films were further characterized by dark and photoconductivity and by photothermal deflection spectroscopy. With respect to films prepared at the conventional frequency of 13.56 MHz considerable differences concerning the electronic and structural properties are observed as the substrate temperature is decreased from 280 to 50 °C. Down to a substrate temperature of 150 °C the electronic film properties change only a little and the total hydrogen content cH and the degree of microstructure that can be directly correlated to cH increase only moderately. Below 150 °C the electronic properties deteriorate in the usual manner but still the total hydrogen content does not exceed 21 at. % even at a substrate temperature of 50 °C. It is argued that the influence of the higher excitation frequency on the plasma and on the growth kinetics plays a key role in this context by allowing a highly effective dissociation of the process gas with the maximum ion energies remaining at low levels. It is concluded that deposition processes at higher excitation frequencies can have important technological implications by allowing a decrease of the deposition temperature without losses in the material quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350500
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  • 7
    Electronic Resource
    Electronic Resource
    Negative ion mass spectra and particulate formation in radio frequency silane plasma deposition experiments (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1341-1343 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Negative ions have been clearly identified in silane rf plasmas used for the deposition of amorphous silicon. Mass spectra were measured for monosilicon up to pentasilicon negative ion radical groups in power-modulated plasmas by means of a mass spectrometer mounted just outside the glow region. Negative ions were only observed over a limited range of power modulation frequency which corresponds to particle-free plasma conditions. The importance of negative ions regarding particulate formation is demonstrated and commented upon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108724
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  • 8
    Electronic Resource
    Electronic Resource
    Direct visual observation of powder dynamics in rf plasma-assisted deposition (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1409-1411 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Contamination due to particles generated and suspended in silane rf plasmas is investigated. Powder is rendered visible by illumination of the reactor volume. This simple diagnostic for global, spatio-temporal powder dynamics is used to study particle formation, trapping, and powder reduction by power modulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105322
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  • 9
    Electronic Resource
    Electronic Resource
    The dispersion relation of an ion beam-plasma system part I: Theory (1978)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 29 (1978), S. 724-724 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01601506
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  • 10
    Electronic Resource
    Electronic Resource
    Application of a cross power spectrum analyzer for low density plasmas (1978)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 29 (1978), S. 359-359 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01601543
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