IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Wednesday Sessions
       Session PS-WeA

Paper PS-WeA9
Atomic-Scale Simulation Study of the Role of H Atoms in the Amorphous to Nanocrystalline Transformation in Plasma-Deposited Silicon Thin Films

Wednesday, October 31, 2001, 4:40 pm, Room 104

Session: Plasma Surface Interactions II
Presenter: S. Sriraman, University of California, Santa Barbara
Authors: S. Sriraman, University of California, Santa Barbara
E.S. Aydil, University of California, Santa Barbara
D. Maroudas, University of California, Santa Barbara
Correspondent: Click to Email
Hydrogenated amorphous (a-Si:H) and nanocrystalline (nc-Si:H) silicon thin films grown by plasma deposition from SiH@sub 4@ and H@sub 2@ containing discharges are widely used in photovoltaic and flat-panel display technologies. When an a-Si:H thin film is exposed to a H@sub 2@ plasma, its nanostructure changes from amorphous to nanocrystalline. Though several hypotheses have been proposed, the fundamental mechanisms behind this transformation are still not well understood. Molecular dynamics (MD) simulations of the interactions of thermal and energetic H atoms with a-Si:H films and their surfaces are used to elucidate the nanoscopic mechanisms behind the amorphous to nanocrystalline transformation. a-Si:H films are deposited through MD simulations of repeated impingement of individual SiH@sub 3@ precursors on an initial H-terminated Si(001)-(2x1) surface. H@sub 2@ plasma exposure is simulated through repeated impingement of individual H atoms onto these a-Si:H films grown by MD. Of the many elementary surface reactions that were identified, Eley-Rideal type H abstraction reactions are believed to mediate strain relaxation processes and promote amorphous to nanocrystalline transformation. The effects of abstraction reactions on the growth surface are examined by analyzing their influence on both local and overall film structure. The surface hydride compositions in the deposited films before and after exposure are compared with experimental data and the comparisons are used to discuss our current understanding of the amorphous to nanocrystalline transformation.