Session X40: Focus Session: Morphology and Evolution at Surfaces: Defects and Transport
8:00 AM–10:12 AM, Friday, March 25, 2005
LACC Room: 408A
Sponsoring Units:
DMP DCMP
Chair: Katsuyo Thornton, University of Michigan
Abstract ID: BAPS.2005.MAR.X40.11
Abstract: X40.00011 : Atomic-Scale Analysis of SiH3 Diffusion on Surfaces of Plasma-Deposited Amorphous Si Thin Films
10:00 AM–10:12 AM
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Abstract 
Authors:
Mayur Valipa
(University of California, Santa Barbara)
Tamas Bakos
(University of Massachusetts, Amherst)
Eray Aydil
(University of California, Santa Barbara)
Dimitrios Maroudas
(University of Massachusetts, Amherst)
Under conditions of low SiH$_{4}$ dissociation during plasma-assisted deposition of hydrogenated amorphous silicon (a-Si:H) thin films, the dominant deposition precursor is the SiH$_{3}$ radical. Device-quality a-Si:H films grown under these conditions are remarkably smooth as the SiH$_{3}$ radical is very mobile on the films' surfaces and fills surface valleys during its diffusion. In this presentation, we discuss atomic-scale mechanisms of SiH$_{3}$ diffusion on a-Si:H surfaces based on molecular-dynamics simulations of SiH$_{3}$ radical impingement on a-Si:H film surfaces. The computed average activation barrier for radical diffusion on the a-Si:H surface is 0.16 eV; this low barrier is due to the weak adsorption of the radical onto the a-Si:H surface and its migration predominantly through overcoordination defects. The mechanisms and energetics of SiH$_{3}$ migration reported for the a-Si:H surface are consistent with our density functional theory calculations on crystalline Si surfaces. The diffusing SiH$_{3}$ radical also incorporates preferentially into surface valleys on the a-Si:H film when it transfers an H atom and forms a Si-Si backbond.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.MAR.X40.11