Local Structural Changes Around Charged Dangling Bonds

Abstract

AbstractTight-binding total energy calculations are used to describe the changes in local structure following either electron or hole capture by a neutral dangling bond in computer generated a-Si:H models. After the change in charge state, the structure is allowed to relax by a steepest descent energy minimization procedure. Generally the local bond angles increase (decrease) rapidly by 3- 100 in transitions from the D0 to the D+ (D-) configurations. The displacement of nearest neighbor atoms and nearby H atoms is large (more than 0.2 Å), but displacement of distant atoms is generally much smaller. Calculated optical transition levels have the D- level below D0 and the D+ level above D0. The fast relaxation of the charged defect configurations suggest a smooth energy surface for the relaxation.