Localized excitations in amorphous silicon alloys

Technical Report · Thu Oct 01 00:00:00 EDT 1987

DOI:https://doi.org/10.2172/7162250· OSTI ID:7162250

The valence band edge of a-Si:H is sensitive to H content, while the conduction band edge is not. The optical gap increases 50% going from the isolated SiH group to the polysilane configuration; the smallest energy gap was for the polycrystal models for a-Si:H. Only the complexes involving the Si dangling bond give rise to active states deep in he a-Si fundamental energy gap. Positions of dangling bond defect state agree with photoluminescence of undoped and oxidized a-Si:H films. Incorporation of halogens into a-Si:H increases the optical gap, quasi-localized states near conduction band tail, and resonances deep in the valence band. Carbon increases the optical gap and produces resonances deep in both bands, while tin does not increase the optical gap and produces resonances in upper part of a-Si:H valence band; this is consistent with a model based on relative strength of Si-Si bond to Si-impurity bond. Effects of P dopant are consistent with models based on P in a-Si:H producing dopant-defect pairs, increased Fermi energy, etc. B substitutional dopants (tetrahedral) produces states near the valence band edge which resemble the show impurity levels in crystalline Si. Trigonally bonded B gives rise to states within the a-Si:H fundamental gap. B-H complexes suggest B-H bonds in B-doped a-Si:H, even at low B contents. Figs, 22 refs. (DLC)

• Research Organization: Morehouse Coll., Atlanta, GA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-84CH10204
• OSTI ID: 7162250
• Report Number(s): DOE/CH/10204-T1; ON: DE93001790
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
14 SOLAR ENERGY
SILICON
CRYSTAL DOPING
ELECTRONIC STRUCTURE
CARBON
COMPLEXES
CRYSTAL DEFECTS
DOPED MATERIALS
ENERGY GAP
HALOGENS
HYDROGENATION
OXYGEN
PHOSPHORUS
PROGRESS REPORT
SILICON SOLAR CELLS
TIN
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
DIRECT ENERGY CONVERTERS
DOCUMENT TYPES
ELEMENTS
EQUIPMENT
MATERIALS
METALS
NONMETALS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SEMIMETALS
SOLAR CELLS
SOLAR EQUIPMENT
360606* - Other Materials- Physical Properties- (1992-)
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