Structural models of a-Si:H with a low defect concentration: A first-principles molecular dynamics study

✍ Scribed by Jarolimek, K. ;de Wijs, G. A. ;de Groot, R. A. ;Zeman, M.

• Book ID: 105365708
• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 321 KB
• Volume: 207
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200982724

✦ Synopsis

Abstract

We present a theoretical study of hydrogenated amorphous silicon (a‐Si:H) with a device quality hydrogen concentration of 11 at%. We used a first principle, parameters‐free method. 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 0.02 K/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. We further calculated the formation energy of dangling bonds (DBs; threefold coordinated Si atom) in all three charge states (negative, neutral, and positive) as a function of the Fermi energy. Interestingly, the DB correlation energies can have both positive and negative values.