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  • 1
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 85.30 ; 86.30 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The electrical properties and the degradation behavior of hydrogenated amorphous silicon alloys (a-Si1−x A x : H, with A=C, Ge, B, P) in designs of pin, pip, nin, and MOS structures are investigated by measuring the dark and light I(V) characteristics and the spectral response as well as the space-charge-limited current (SCLC), the time of flight (TOF) of carriers and the field effect (FE). These investigations give an overview of our recent work combined with new results emphasizing the physics of the a-Si:H pin solar cells. We discuss the stabilizing influence on the degradation behavior achieved by profiling the i layers of the pin solar cells with P and B. Two kinds of pin solar cells, namely glass/SnO2/p(C)in/metal and glass/metal/pin/ITO, are investigated and an explanation of their different spectral response behavior is given. SCLC measurements lead to the conclusion that trapping is also involved in the degradation mechanism, as is recombination. TOF experiments on a-Si1−x Ge x : H pin diodes indicate that the incorporation of Ge widens the tail-state distribution below the conduction band. FE measurements showed densities of gap states of about 5×l016cm−3eV−1.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2264-2271 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic properties of hydrogen in carbon-doped n-type silicon have been studied using deep-level transient spectroscopy. It is demonstrated that hydrogen (H) in the presence of substitutional carbon (C) forms an H-C complex with an energy level located ≈0.16 eV below the edge of the conduction band. The H-C complex is a deep donor which is only stable in the positively charged state and dissociates after capture of free electrons for temperatures T≥300 K. The H-C dissociation kinetics yield an activation energy of 0.73 eV.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1683-1685 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The defect density ND of hydrogenated amorphous germanium (a-Ge:H) has been studied as a function of the Fermi level position EF using photothermal deflection spectroscopy. A strong increase of ND is observed as EF is shifted towards either one of the band edges by doping with boron or phosphorus, respectively. This behavior is similar to that of amorphous silicon (a-Si:H) and can be explained by a hydrogen-mediated equilibrium between weak bonds and dangling bonds. From a fit of this model to our data the lowest limit of the defect density in a-Ge:H is estimated to be 2×1016 cm−3, which is larger by about two orders of magnitude than in a-Si:H. The reason for this difference is the smaller band gap of a-Ge:H which entails smaller formation energies of dangling-bond defects than in a-Ge:H.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2110-2114 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new theoretical insight in the dynamics of position-dependent deep trapping within the p/i-interface region of a-Si:H p-i-n diodes is presented. The positive space charge in this region relates internal electric field and deep trapping electron lifetime profiles with each other. A hyperbolic field dependence and a position-independent capture constant can explain well the experimental delayed field time of flight results.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2016-2023 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous Si1−xGex:H films and p-i-n diodes were fabricated by decomposition of SiH4/GeH4 mixtures in a triode glow-discharge reactor. The photoconductivity under AM1 illumination in these alloys was constant over a range of band gaps between 1.8 (x=0) and 1.5 eV (x=0.25), while the solar cell conversion efficiency decreased at the same time from 8.6% to 4.3%. This can be explained by a reduction in the μτ product for holes with rising x in undoped samples as revealed by time-of-flight experiments. In contrast to μτ, the hole drift mobility μD,h remains constant. The opposite behavior is observed for electrons, whose drift mobility μD,e decreases as the mobility activation energy EA increases. The relation between EA and μD,e for variable x is suggestive of the Meyer–Neldel rule for the conductivity. In conjunction with space-charge-limited current and sub-band-gap absorption data we conclude that only the conduction-band tail is widened by the incorporation of Ge while the valence-band tail remains unaffected. The transport data for x〉0 can no longer be explained by a purely exponential conduction-band tail. The rising density of midgap states shows an increasing capture cross section for holes and a decreasing one for electrons.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 5051-5054 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of deep traps in the depletion regions of Schottky barrier junctions on silicon was made using deep level transient spectroscopy (DLTS). The Si samples, which had different carbon contents (C), were exposed to several annealing processes. The measurements show that depending on the C concentration and the annealing process employed C-induced deep traps with activation energies of 355, 290, and 216 meV appear above the valence band. The density, the trap levels, and the capture cross sections of these C-induced traps were determined from the DLTS data. The deep trap densities are correlated with the behavior of the diffusion length of the minority carriers in the different Si materials.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0630
    Keywords: Solid state laser ; Pump threshold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report on room temperature cw oscillation of a scandium neodymium pentaphosphate (Sc: NdP5O14) laser pumped with an argon laser. The threshold pump power is, to our knowledge, the lowest obtained so far at room temperature with any laser material.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 46 (1988), S. 5-8 
    ISSN: 1432-0630
    Keywords: 73.60 ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Measurements of steady-state photoconductivity with respect to light-induced defect generation in amorphous hydrogenated silicon (a-Si: H) show that the power index of the time evolution (long-term observation) of the photodegradation is determined by the exposure temperature and the material.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0630
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The pentaphosphate system Nd1−x Y x P5O14 covers four crystalline phases with five different site geometries for Nd. We determined the4F3/2,4I13/2,4I11/2,4I9/2 stark levels and identified the sites spectroscopically, including the case of the monoclinic layer structureC2/c which has two Nd sites. Crystal field calculations for the energy levels in the monoclinic phaseP2 1/c and the orthorhombic phasepnma with tetragonal and orthorhombic site symmetry approximations are reasonable but reveal their shortcomings. As a consequence, we consider it improper to try to calculate rare-earth optical transition probabilities with approximate crystal fields. Random distribution of Nd and Y causes inhomogeneous broadening (∼6 Å) which peaks atx=0.5. Thermal equilibrium between the4F3/2 levels is reached within 2–5×10−13 sec. The three room temperature modifications could be lased cw. Pure NdP5O14 was found to be the best laser.
    Type of Medium: Electronic Resource
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