Effects of High Electric Fields on Tunneling-Assisted Optical Electron Transitions in a-Si

A theoretical model for the optical absorption of amorphous silicon (a-Si) at high electric field aimed for ease of use is developed. Optical absorption is proportional to the number of possible transitions from valence band to conduction band. When an electron is excited by a photon, the atom it wa...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2011-12, Vol.58 (12), p.4318-4323
Main Authors: Pirc, M., Furlan, J.
Format: Article
Language:English
Subjects:
Absorption
Absorption coefficient
amorphous silicon (a-Si)
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electric fields
Electric potential
Electron optics
Energy states
Exact sciences and technology
high electric fields
Integrated optics
modeling
optical electron transitions
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of bulk materials and thin films
Photonics
Physics
Tunneling
tunneling-assisted transitions
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Summary:A theoretical model for the optical absorption of amorphous silicon (a-Si) at high electric field aimed for ease of use is developed. Optical absorption is proportional to the number of possible transitions from valence band to conduction band. When an electron is excited by a photon, the atom it was bound to is ionized and bends all the energy levels to form a Coulombic potential funnel. A high electric field tilts all the energy levels. The Coulombic funnel and the tilted conduction band form a potential barrier through which an electron can tunnel, giving rise to additional available density of conduction band states, thus increasing the optical absorption. The model was used to calculate the optical absorption at zero electric field, 100 kV/cm, and 1 MV/cm. Results show that, although optical absorption change is barely perceptible at electric fields up to 100 kV/cm, the change is much more pronounced at an electric field strength of 1 MV/cm.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2011.2169068