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  • 1
    Electronic Resource
    Electronic Resource
    Injection and Collection Diffusion Lengths of Polycrystalline Thin-Film Solar Cells (1999)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 67-68 (Apr. 1999), p. 81-88 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/26/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.67-68.81.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Note on the interpretation of injection-level-dependent surface recombination velocities (1995)
    Springer
    Applied physics 60 (1995), S. 523-524 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 73.40
    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 surface recombination velocity S=U/n is defined as the ratio between the surface recombination current density U and the excess minority carrier concentration n at the semiconductor surface. Measurements of injection-dependent surface recombination velocities apply modulation techniques, and thus, in reality, a differential surface recombination velocity S diff = dU/dn is determined. The significance to distinguish S and S diff when evaluating measurements is shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538780
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  • 3
    Electronic Resource
    Electronic Resource
    Modeling light trapping and electronic transport of waffle-shaped crystalline thin-film Si solar cells (1999)
    Springer
    Applied physics 69 (1999), S. 201-213 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 84.60.J; 42.15.D; 72.20.Jv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Monocrystalline Si films from the novel perforated-Si process are candidates for the fabrication of thin-film solar cells because their waffle shape enhances the optical absorption and hence permits the use of films with a thickness of only a few microns. We study the optics of waffle cells by three-dimensional Monte Carlo ray-tracing. A high photogeneration of 38 mA/cm2 from a film of thickness Wf=4 μm is possible due to a detached Al-back surface reflector that has an effective reflectance of 99.7% at 1250 nm. Our analytical model for light trapping in thin films explains this high reflectance. Two-dimensional numerical transport modeling reveals the existence of an optimum texture period p≈2Wf that originates from a carrier collection efficiency that increases with texture period while the photogeneration decreases with period. For well-passivated cells the optimum thickness Wf is at least one fifth of the diffusion length L. Efficiencies of 17% to 18% are feasible with waffle films of 1 to 3 μm in thickness. We introduce an analytic model for the minority carrier transport that agrees with two-dimensional numerical modeling to within 10% and reduces the computation time by orders of magnitude. This analytic model is also applicable to conformal thin-film geometries differing from the waffle geometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050991
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  • 4
    Electronic Resource
    Electronic Resource
    Independent fourth-order elastic coefficients for all crystal classes (1979)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 35 (1979), S. 525-533 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Numerical methods can be used to obtain the dependence relations between components of an nth-rank tensor for the particular symmetries of each crystal class. The program has been used successfully to calculate the fourth-order elastic coefficients, corresponding to a tensor of eighth rank for all crystal classes and the isotropic case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739479001261
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  • 5
    Electronic Resource
    Electronic Resource
    Plasma-deposited silicon nitride on ultrathin silicon oxide films investigated by infrared grazing internal reflection spectroscopy (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4811-4816 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrathin silicon nitride films of 0.4–4.0 nm thickness prepared by remote plasma-enhanced chemical-vapor deposition (RPECVD) and direct plasma-enhanced CVD (DPECVD), respectively, are investigated by infrared grazing internal reflection spectroscopy. The ultrathin silicon nitride films are deposited on top of a 1.3 nm silicon oxide film thermally grown on crystalline silicon. From the spectra it is concluded that the vibrational properties of the 1.3 nm silicon oxide layer have strongly changed after deposition of a thin DPECVD silicon nitride, while the vibrational properties of the 1.3 nm oxide are nearly unchanged after deposition of a RPECVD silicon nitride film. The infrared spectra are analyzed by simulating the measured spectra with a dielectric function model that accounts for the amorphous film structure. An analytic formula for this dielectric function model is derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357253
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  • 6
    Electronic Resource
    Electronic Resource
    Infrared observation of thermally activated oxide reduction within Al/SiOx/Si tunnel diodes (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4377-4381 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron-beam-evaporated aluminum/silicon oxide/silicon tunnel diodes with an initial oxide thickness of 1.3 nm have been annealed for up to 1 h at temperatures from 213 to 369 °C. They have been investigated by infrared grazing internal reflection (GIR) spectroscopy and current-voltage measurements. The measured IR spectra were analyzed by computer modeling. All spectral features could be explained self-consistently within a Al/AlOy/SiOx/Si layer model. In the as-deposited state less than 0.6 monolayers of Al—O bonds are formed at the Al/SiOx interface. A thermally activated reduction of the ultrathin oxide film by Al was observed. The changes in the current-voltage curves induced by slight annealing (1 min at 213 °C) are accompanied by changes in the insulator-bonding structure, which GIR is sensitive enough to detect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350774
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  • 7
    Electronic Resource
    Electronic Resource
    The concept of effective film thickness for the determination of bond concentrations from IR spectra of weakly absorbing thin films on silicon (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7395-7399 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin-film bond concentrations can be determined from infrared transmission and reflection spectra. Simply using the Lambert–Beer law can lead to errors of 80%. The concept of effective film thickness presented here avoids these errors and still allows a quick determination of the absorption coefficient without using a computer. It fully takes into account the effects of multiple reflections. For weakly absorbing thin films on silicon the effective film thickness was calculated numerically (i) for normal incidence transmission spectra and (ii) for 20° reflection spectra with a mirror behind the sample. The latter method is of general interest for the investigation of weak absorptions as it avoids the disturbing interference oscillations and its sensitivity is about twice that of a transmission measurement. The numerical results are verified experimentally for Si-H and N-H vibrations in plasma silicon nitride and analytically for the thin-film limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347552
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  • 8
    Electronic Resource
    Electronic Resource
    An infrared dielectric function model for amorphous solids (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1-6 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For the modeling of infrared spectra it is a common approach to use a dielectric function that treats the vibrational modes as damped harmonic oscillators. This model was found to be rather crude for some applications to amorphous solids. A dielectric function model yielding a Gaussian shape of the absorption lines and satisfying Kramers–Kronig relations is suggested. The model function is constructed by a convolution of a Gaussian function with the dielectric function of the damped harmonic oscillator model. An analytical solution of this integral is given. It is demonstrated that this model describes the spectra of thermally grown ultrathin (1.3 nm) silicon oxide films, plasma-deposited silicon films, plasma-deposited silicon nitride films, and amorphous aluminum oxide films very well. The physical motivation of the dielectric function model suggested is the randomness of the vibrational frequencies in an amorphous structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350737
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  • 9
    Electronic Resource
    Electronic Resource
    A highly sensitive infrared spectroscopic method for buried thin low-index films (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 794-796 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A technique for the infrared spectroscopy of thin low-index films buried in a high-index material is introduced. The measurement technique applies a grazing incidence transmission of p-polarized light. The sensitivity enhancement over a transmission measurement is treated analytically for the thin film limit and is verified numerically by the simulation of spectra of ultrathin silicon oxide films within silicon as produced by wafer bonding. The technique can also be applied to hydrogen platelets within heavily hydrogenated silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351814
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  • 10
    Electronic Resource
    Electronic Resource
    Solar cell efficiency and carrier multiplication in Si1−xGex alloys (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 4213-4221 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Crystalline Si1−xGex compounds offer the possibility for tuning the electronic energy band structure with the chemical composition of the alloy in order to adapt the material for devices utilizing the energy of solar photons at an optimum. We concentrate on the efficiency enhancement due to carrier multiplication by impact ionization. We calculate the internal quantum efficiency and the possible solar cell efficiency for this material system. The number of impact-generated charge carriers is obtained by a simulation of the competing carrier–carrier and carrier–photon scattering processes. These calculations show that the wave vector dependence of the scattering processes is unimportant for good agreement between theoretical and experimental quantum efficiencies in Si and Ge. Finally, we calculate solar cell efficiencies under the ideal assumption of unity collection efficiency and radiative recombination only. Impact ionization enhances the theoretical conversion efficiency by 0.5 percentage point; this improvement is curtailed by the strong phonon emission probability of hot carriers. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367177
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