Structure of a-Si:H from Harris-functional molecular dynamics

Using Harris-functional molecular dynamics, we generate a 242-atom model of hydrogenated amorphous silicon. Our model has a hydrogen concentration of 11%, which is in the range of device-quality films. To produce our model, we first form a liquid at ∼1800 K and then quench to produce an amorphous structure at ∼300 K. We find our model produces radial distribution functions, which compare favorably with previous experimental and theoretical results. We investigate the limitations of molecular-dynamics-based methods for producing amorphous structures. In addition, we examine the hydrogen structures present, which include isolated SiH bonds and clusters of 2-7 Si-H bonds. The role of hydrogen and the relevance of these clusters is discussed.