ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Ellipsometric study of a-Si:H thin films deposited by square wave modulated rf glow discharge (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 632-638 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of hydrogenated amorphous silicon (a-Si:H), deposited by square wave modulated (SQWM) rf silane discharges, have been studied through spectroscopic and real time phase modulated ellipsometry. The SQMW films obtained at low mean rf power density (19 mW/cm2) have shown smaller surface roughness than those obtained in standard continuous wave (cw) rf discharges. At higher rf powers (≥56 mW/cm2), different behaviors depending on the modulating frequency have been observed. On the one hand, at low modulating frequencies (〈40 Hz), the SQWM films have shown a significant increase of porosity and surface roughness as compared to cw samples. On the other, at higher modulating frequencies, the material density and roughness have been found to be similar in SQWM and cw films. Furthermore, the deposition rate of the films show more pronounced increases with the modulating frequency as the rf power is increased. Experimental results are discussed in terms of plasma negative charged species which can be relatively abundant in high rf power discharges and cause significant effects on the deposited layers through polymers, clusters, and powder formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347343
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    In situ spectroellipsometric study of the nucleation and growth of amorphous silicon (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2752-2759 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed in situ spectroellipsometric analysis of the nucleation and growth of hydrogenated amorphous silicon (a:Si:H) is presented. Photoelectronic quality a-Si:H films are deposited by plasma-enhanced chemical vapor deposition on smooth metal (NiCr alloy) and crystalline silicon (c-Si) substrates. The deposition of a-Si:H is analyzed from the first monolayer up to a final thickness of 1.2 μm. In order to perform an improved analysis, real time ellipsometric trajectories are recorded, using fixed preparation conditions, at various photon energies ranging from 2.2 to 3.6 eV. The advantage of using such a spectroscopic experimental procedure is underlined. New insights into the nucleation and growth mechanisms of a-Si:H are obtained. The nucleation mechanism on metal and c-Si substrates is very accurately described assuming a columnar microstructural development during the early stage of the growth. Then, as a consequence of the incomplete coalescence of the initial nuclei, a surface roughness at the 10–15 A(ring) scale is identified during the further growth of a-Si:H on both substrates. The bulk a-Si:H grows homogeneously beneath the surface roughness. Finally, an increase of the surface roughness is evidenced during the long term growth of a-Si:H. However, the nature of the substrate influenced the film growth. In particular, the film thickness involved in the nucleation-coalescence phase is found lower in the case of c-Si (67±8 A(ring)) as compared to NiCr (118±22 A(ring)). Likewise films deposited on c-Si present a smaller surface roughness even if thick samples are considered (〉1 μm). More generally, the present study illustrates the capability of in situ spectroellipsometry to precisely analyze fundamental processes in thin-film growth, but also to monitor the preparation of complex structures on a few monolayers scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346452
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effect of substrate temperature on deposition rate of rf plasma-deposited hydrogenated amorphous silicon thin films (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3757-3759 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a study about the influence of substrate temperature on deposition rate of hydrogenated amorphous silicon thin films prepared by rf glow discharge decomposition of pure silane gas in a capacitively coupled plasma reactor. Two different behaviors are observed depending on deposition pressure conditions. At high pressure (30 Pa) the influence of substrate temperature on deposition rate is mainly through a modification of gas density, in such a way that the substrate temperature of deposition rate is similar to pressure dependence at constant temperature. On the contrary, at low pressure (3 Pa), a gas density effect cannot account for the observed increase of deposition rate as substrate temperature rises above 450 K with an activation energy of 1.1 kcal/mole. In accordance with laser-induced fluorescence measurements reported in the literature, this rise has been ascribed to an increase of secondary electron emission from the growing film surface as a result of molecular hydrogen desorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348470
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Properties of amorphous silicon thin films grown in square wave modulated silane rf discharges (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1546-1548 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogenated amorphous silicon (a-Si:H) thin films have been obtained from pure SiH4 rf discharges by using the square wave modulation (SQWM) method. Film properties have been studied by means of spectroellipsometry, thermal desorption spectrometry, photothermal deflection spectroscopy and electrical conductivity measurements, as a function of the modulation frequency of the rf power amplitude (0.2–4000 Hz). The films deposited at frequencies about 1 kHz show the best structural and optoelectronic characteristics. Based upon the experimental results, a qualitative model is presented, which points up the importance of plasma negative ions in the deposition of a-Si:H from SQWM rf discharges through their influence on powder particle formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351229
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    In situ fast ellipsometric analysis of repetitive surface phenomena (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3135-3139 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present an ellipsometric technique and ellipsometric analysis of repetitive phenomena, based on the experimental arrangement of conventional phase modulated ellipsometers (PME) conceived to study fast surface phenomena in repetitive processes such as periodic and triggered experiments. Phase modulated ellipsometry is a highly sensitive surface characterization technique that is widely used in the real-time study of several processes such as thin film deposition and etching. However, fast transient phenomena cannot be analyzed with this technique because precision requirements limit the data acquisition rate to about 25 Hz. The presented new ellipsometric method allows the study of fast transient phenomena in repetitive processes with a time resolution that is mainly limited by the data acquisition system. As an example, we apply this new method to the study of surface changes during plasma enhanced chemical vapor deposition of amorphous silicon in a modulated radio frequency discharge of SiH4. This study has revealed the evolution of the optical parameters of the film on the millisecond scale during the plasma on and off periods. The presented ellipsometric method extends the capabilities of PME arrangements and permits the analysis of fast surface phenomena that conventional PME cannot achieve. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148257
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Microstructure of highly oriented, hexagonal, boron nitride thin films grown on crystalline silicon by radio frequency plasma-assisted chemical vapor deposition (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6553-6555 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a high-resolution electron microscopy study of the microstructure of boron nitride thin films grown on silicon (100) by radio-frequency plasma-assisted chemical vapor deposition using B2H6 (1% in H2) and NH3 gases. Well-adhered boron nitride films grown on the grounded electrode show a highly oriented hexagonal structure with the c-axis parallel to the substrate surface throughout the film, without any interfacial amorphous layer. We ascribed this textured growth to an etching effect of atomic hydrogen present in the gas discharge. In contrast, films grown on the powered electrode, with compressive stress induced by ion bombardment, show a multilayered structure as observed by other authors, composed of an amorphous layer, a hexagonal layer with the c-axis parallel to the substrate surface and another layer oriented at random. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363677
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Growth of diamond films on boron nitride thin films by bias-assisted hot filament chemical vapor deposition (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1682-1684 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the growth of continuous diamond thin films by bias-assisted hot filament chemical vapor deposition onto hexagonal boron nitride films prepared by plasma chemical vapor deposition on silicon substrates. Negative substrate biasing during the early stages of diamond growth greatly increased the nucleation density. Values of 1010 cm−2 were achieved at −250 V for bias times as short as 25 min. After the nucleation stage, high quality polycrystalline continuous diamond films, as revealed by scanning electron microscopy and Raman analysis, were grown under standard hot filament deposition conditions. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118668
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Using thermal and hydrothermal time to model seedling emergence of Avena sterilis ssp. ludoviciana in Spain (2005)
    Oxford, UK : Blackwell Science Ltd
    Weed research 45 (2005), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Historical records on the field emergence of seedlings of Avena sterilis in winter cereal crops were used to develop thermal/hydrothermal models to predict the emergence of this weed as a function of meteorological conditions. When water was not a limiting factor, a Weibull function provided a good description of the relationship between thermal time and seedling emergence. The variability in the rate of seedling emergence observed under these conditions was associated with variation in the differential between measured and base temperatures. When water was limiting in the soil, the rate of seedling emergence was reduced, a different function was required to describe the process. The use of a hydrothermal model enabled the use of a single function to describe the patterns of seedling emergence of the nine site-years considered in the study. Using this model we can conclude that 70% seedling emergence will be reached, under very diverse conditions, within 300 hydrodegree days. The hydrothermal model proposed was validated with independent seedling emergence data, supporting the idea that this model is robust enough to be used as a predictive tool for seedling emergence of A. sterilis in a variety of conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3180.2004.00444.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Wild oat (Avena sterilis L.) competition with winter barley: plant density effects (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 31 (1991), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The competitive interactions between Avena sterilis ssp. ludoviciana (Dur.) Nyman and winter barley have been studied, taking into consideration the densities of both species. As the density of A. sterilis increased, barley yield decreased exponentially. A 10% reduction in yield was found with wild oat densities ranging from 20–80 panicles m–2, and yield losses reached 50%, with densities of 〉300 panicles m–2, Barley grain yield was reduced by wild oats through a reduction in the number of fertile tillers. Climatic conditions during the growing seasons affected the response of barley to wild oat competition. In general, barley yields were relatively unaffected by seeding rates, with similar responses observed in the presence and in the absence of wild oat infestations. However, the highest yield losses were obtained with the lowest seeding rate (100 kg ha–1). Furthermore, low barley densities allowed the wild oat plants to produce more seeds, increasing the potential infestation during the following season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3180.1991.tb01770.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Characterization of the germination and emergence response to temperature and soil moisture of Avena fatua and A. sterilis (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 30 (1990), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Seeds of Avena fatua L. and )A. sterilis L. were germinated under a wide range of temperatures (5–30°C) and osmotic potentials (−25 to −1400 KPa) in order to characterize their responses to these two environmental factors. Although both species behaved similarly at moderate temperatures, different responses were observed at the two extremes. )A. sterilis germinated and emerged in a higher proportion than A. fatua at temperatures below 10°C but the opposite was true at temperatures above 20°C. Although the rates of these two processes were similar in both species up to 18°C, above this temperature the germination and emergence of )A. sterilis was considerably delayed in comparison with that of A. fatua. The effect of decreasing osmotic potentials in reducing the germination was more pronounced in A. sterilis than in A. fatua. However, no differences were observed in the emergence responses of either species. The adaptative advantages of these characteristics and their relationship with the geographic distribution of the two species is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3180.1990.tb01715.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...