Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon

Journal Article · Wed Oct 01 04:00:00 EDT 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.56.9197· OSTI ID:543809

Biswas, R; Li, Q; Yoon, Y ^[1]; Branz, H M ^[2]

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1. Department of Physics and Astronomy, Microelectronics Research Center and Ames Laboratory, U.S. Department of Energy, Iowa State University, Iowa 50011 (United States)
2. National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

Tight-binding molecular-dynamics calculations are utilized to study the spatial extent and time scales of the structure relaxation, following a change of the charge state of dangling bonds in hydrogenated amorphous silicon. Structural relaxation is found to be local, primarily involving large displacements ({gt}0.1{Angstrom}) of the nearest neighbors of the dangling bond and of a few nearby H atoms. Calculated optical transition levels have the D{sup {minus}} level below both D{sup 0} levels and the D{sup +} level above the D{sup 0} levels. A smooth energy surface is found for transitions between the neutral and charged dangling-bond configurations. Molecular-dynamics simulations show that electron levels relax in tens of picoseconds following electron capture or emission by a dangling bond, but large oscillations of the gap levels may be present as a result of the strong coupling between the charge and local structure. The results do not appear to support either the slow relaxation model of Cohen, Leen, and Rasmussen, or the D structural memory model of Branz and Fedders. {copyright} {ital 1997} {ital The American Physical Society}

• Research Organization: National Renewable Energy Laboratory
• DOE Contract Number: AC36-83CH10093; W-7405-ENG-82
• OSTI ID: 543809
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 15 Vol. 56; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
CHARGE STATES
CHEMICAL BONDS
HYDROGENATION
MOLECULAR DYNAMICS METHOD
RELAXATION
SEMICONDUCTOR MATERIALS
SILICON