Abstract
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 (>0.1 ..ANG..) of the nearest neighbors of the dangling bond and of a few nearby H atoms.Calculated optical transition levels have the D- level below both D0 levels and the D+ level above the D0 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 ofthe 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.
Original language | American English |
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Pages (from-to) | 9197-9200 |
Number of pages | 4 |
Journal | Physical Review B |
Volume | 56 |
Issue number | 15 |
DOIs | |
State | Published - 1997 |
NREL Publication Number
- NREL/JA-520-24435