A theoretical study was made of hydrogenated amorphous silicon (a-Si:H) with a device quality hydrogen concentration of 11at%. A first-principles parameter-free method was used. The interaction between the atoms was treated quantum mechanically within the density functional theory approximation. Amorphous structures were prepared by cooling from the liquid phase. When using a cooling rate of 0.02K/fs defect-free structures were prepared. All silicon atoms were fourfold coordinated and there were no defect states in the band gap. The calculated short range order showed a good agreement with available neutron scattering measurements. Also calculated was the formation energy of dangling bonds in all three charge states (negative, neutral, positive) as a function of the Fermi energy. Interestingly, the dangling bond correlation energies could have both positive and negative values.

Structural Models of a-Si:H with a Low Defect Concentration - a First-Principles Molecular Dynamics Study. K.Jarolimek, G.A.de Wijs, R.A.de Groot, M.Zeman: Physica Status Solidi A, 2010, 207[3], 605-8