Temperature dependent vibrational spectra in non-crystalline materials: application to hydrogenated amorphous silicon

摘要

We present a novel approach for parameter-free modeling of the structural,dynamical and electronic properties of non-crystalline materials based onab-initio Molecular Dynamics, improved signal processing technique and computervisualization. The method have been extensively tested by investigatinghydrogen and silicon dynamics in hydrogenated amorphous silicon (a-Si:H). Bycomparing the theoretical and experimental vibrational spectra we demonstratehow to relate vibrational properties to the structural stability, bonding andhydrogen diffusion. We extracted microscopic characteristics that cannot beobtained by other techniques, namely hydrogen migration and related bondswitching, dangling bond passivation, low hydrogen activation energy, anda-Si:H stability in general, and we show, via the analysis of a test case, thatour method provides a rigorous and realistic description of non-crystallinematerials. We also demonstrate that this method offers the possibility ofaccessing other important macroscopic characteristics of amorphous silicon andcan be used to model all the aspects of a-Si:H dynamics, including thedetrimental Staebler-Wronski effect.