Fabian, Jaroslav and Feldman, Joseph L. and Hellberg, C. Stephen and Nakhmanson, S. M. (2003) Numerical study of anharmonic vibrational decay in amorphous and paracrystalline silicon. Physical Review B 67 (22), p. 224302.
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Other URL: http://link.aps.org/abstract/PRB/v67/e224302
The anharmonic decay rates of atomic vibrations in amorphous silicon (a-Si) and paracrystalline silicon (p-Si), containing small crystalline grains embedded in a disordered matrix, are calculated using realistic structural models. The models are 1000-atom four-coordinated networks relaxed to a local minimum of the Stillinger-Weber interatomic potential. The vibrational decay rates are calculated numerically by perturbation theory, taking into account cubic anharmonicity as the perturbation. The vibrational lifetimes for a-Si are found to be on picosecond time scales, in agreement with the previous perturbative and classical molecular dynamics calculations on a 216-atom model. The calculated decay rates for p-Si are similar to those of a-Si. No modes in p-Si reside entirely on the crystalline cluster, decoupled from the amorphous matrix. The localized modes with the largest (up to 59%) weight on the cluster decay primarily to two diffusons. The numerical results are discussed in relation to a recent suggestion by van der Voort et al. [Phys. Rev. B 62, 8072 (2000)] that long vibrational relaxation inferred experimentally may be due to possible crystalline nanostructures in some types of a-Si.
|Institutions:||Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Jaroslav Fabian|
|Subjects:||500 Science > 530 Physics|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Owner:||Prof. Dr. Jaroslav Fabian|
|Deposited On:||20 Mar 2007|
|Last Modified:||20 Jul 2011 21:03|