OPTICAL, MODULATED OPTICAL AND RAMAN SCATTERING STUDY OF HYDROGENATED AND FLUORINATED AMORPHOUS SILICON.
Item
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Title
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OPTICAL, MODULATED OPTICAL AND RAMAN SCATTERING STUDY OF HYDROGENATED AND FLUORINATED AMORPHOUS SILICON.
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Identifier
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AAI8302519
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identifier
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8302519
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Creator
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JAN, GWO-JEN.
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Contributor
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Fred H. Poliak
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter
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Abstract
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The prominent features in the optical properties of semiconductors due to the long range order and hence are sensitive to disorder. In order to gain information about the nature of disorder in hydrogenated amorphous silicon (a-Si:H) and hydrogenated and fluorinated amorphous silicon (a-Si:F:H) the Raman scattering, optical and modulated optical (Electrolyte Electroreflectance, EER) spectra of (a) high temperature thermally annealed (HTA) a-Si:H(B), as well as unannealed a Si:H(B) and a Si.H(P), (b) heavily doped n-type a-Si:F:H with microcrystalline ((mu)c) structure and (c) lightly doped a Si:F:H were studied. Comparison had been made with the optical features of crystalline silicon (c-Si). EER studies of ion-damaged, laser-annealed Si were also performed.;In the Raman spectra of (a) HTA-a-Si:H(B) and (b) a-Si:F:H alloys with (mu)c-structure we have observed Raman frequencies intermediate between these of the amorphous phase (480 cm('-1)) and the crystalline phase (522 cm('-1)). The results for Si:F:H have been interpreted in terms of the (mu)c structure and the related relaxation of the(' )q-vector restrictions. However, the structure for the HTA-a-Si:H are somewhat more complex since there is also a Fano-shift due to the high doping level.;For the modulated optical spectra we have obtained energy features at 3.4 eV and 4.5 eV (which are related to the optical transitions for c-Si) in HTA-a-Si:H, heavily doped n-type Si:F:H alloys ((mu)c structure) as well as ion-damaged, laser-annealed Si. The EER spectra of HTA-a-Si:H showed features very similar to the ion-damaged, laser-annealed Si. No EER spectra was observed in unannealed Si:H(B) and lightly doped n-type Si:F:H specimens.;The reflectivity and the imaginary part of the dielectric function, (epsilon)(,2)((omega)), of (a) high temperature annealed, as well as unannealed, a-Si:H(B) and (b) n-type Si:F:H alloys with uc structure have been investigated in the energy range 1 - 10 eV. Unannealed Si:H(B) showed the featureless single bump spectra which is characteristics of amorphous Si. However, we have found that the HTA-a Si:H(B) and highly doped n-type Si:F:H samples exhibited well-defined structures associated with those of c-Si. The electron number per single Si-atom contributing the optical transition is calculated from a Kramers-Kronig analysis.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Physics
