Dangling-bond levels and structure relaxation in hydrogenated amorphous silicon
- Department of Physics and Astronomy, Microelectronics Research Center and Ames Laboratory, U.S. Department of Energy, Iowa State University, Iowa 50011 (United States)
- 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 Lab. (NREL), Golden, CO (United States)
- DOE Contract Number:
- AC36-83CH10093; W-7405-ENG-82
- OSTI ID:
- 543809
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 56, Issue 15; Other Information: PBD: Oct 1997
- Country of Publication:
- United States
- Language:
- English
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