AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS+EL-WeM

Paper SS+EL-WeM5
Simulations of Surface Diffusion on Amorphous Silicon

Wednesday, November 6, 2002, 9:40 am, Room C-110

Session: Nucleation & Growth of Semiconductors
Presenter: A.S. Dalton, University of Illinois
Authors: A.S. Dalton, University of Illinois
E.G. Seebauer, University of Illinois
Correspondent: Click to Email
Surface diffusion over amorphous materials plays a governing role in an increasing variety of applications, including reflow of amorphous metals and oxides, and nanostructure formation for electronic memory devices. However, there exists little literature describing diffusion on amorphous surfaces. The structural and energetic heterogeneity of amorphous surfaces should lead to diffusivities that differ significantly from crystalline ones. Our recent experimental work has confirmed that that activation energy for surface-self diffusion on amorphous Si (a-Si) differs significantly from that for crystalline Si (c-Si), and that the activation energy is temperature dependent. Here we describe the results of molecular dynamics simulations to gain atomistic insights into these phenomena. Calculations using a modified Stillinger-Weber potential confirm marked differences between diffusion parameters on a-Si vs. c-Si, with lower activation energies for a-Si. Collective motions involving two or three atoms play a significant role, as do long hops over several atomic diameters. Both hopping motion and formation of mobile atoms can be described with distribution functions, which ultimately give rise to temperature-dependent Arrhenius parameters for diffusion.