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Grain Nucleation and Grain Growth During Crystallization of HWCVD a-Si:H Films

Published online by Cambridge University Press:  01 February 2011

S. P. Ahrenkiel ,
B. Roy ,
A. H. Mahan  and
D. S. Ginley
S. P. Ahrenkiel
Affiliation:
National Center for Photovoltaics, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO, 80401
B. Roy
Affiliation:
baroy@mines.edu, Colorado School of Mines, Metallurgical & Materials Engineering, Golden, CO, 80401, United States
A. H. Mahan
Affiliation:
harv_mahan@nrel.govNational Renewable Energy LaboratoryNational Center for Photovoltaics1617 Cole Blvd.GoldenCO80401United States
D. S. Ginley
Affiliation:
david_ginley@nrel.gov, National Renewable Energy Laboratory, National Center for Photovoltaics, 1617 Cole Blvd., Golden, CO, 80401, United States
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Abstract

Hydrogenated amorphous silicon (a-Si:H) films of high and low hydrogen content were deposited directly on molybdenum, carbon-coated TEM grids by hot-wire chemical vapor deposition. The material was annealed at 600°C and 630°C for variable times to achieve various degrees of crystallinity. The films thickness of 100-nm allowed characterization by TEM without additional thinning. The grain growth in such thin films is nearly two-dimensional, allowing clear identification of crystalline and amorphous regions. Thus, the crystalline volume fraction can be tracked by simple image-processing methods. The evolution of crystallization by grain nucleation and growth for these films is accurately described by classical phase-change kinetics. Analysis of the randomly distributed grains at early stages of crystallization also provides the average areal grain number density and grain size. From the image analysis, we determine the grain nucleation rate and the grain growth velocity. The final grain size is then estimated by extrapolation to the fully crystallized state, assuming the kinetic parameters remain constant after the onset of crystallization.

Keywords

crystal growthchemical vapor deposition (CVD) (deposition)transmission electron microscopy (TEM)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 910: Symposium A – Amorphous and Polycrystalline Thin-Film Silicon Science and Technology – 2006 , 2006 , 0910-A07-05
Copyright
Copyright © Materials Research Society 2006

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