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Propagation and Density Reduction of Threading Dislocations in SiC Crystals during Sublimation Growth

Published online by Cambridge University Press:  01 February 2011

Ping Wu
Affiliation:
pwu@ii-vi.com, II-VI Incorporated, Wide Bandgap Materials Group, 20 Chapin Rd., Suite 1005, Pine Brook, NJ, 07058, United States
Xueping Xu
Affiliation:
xxu@ii-vi.com, II-VI Incorporated, Wide Bandgap Materials Group, 20 Chapin Rd., Suite 1005, Pine Brook, NJ, 07058, United States
Varatharajan Rengarajan
Affiliation:
vrengarajan@ii-vi.com, II-VI Incorporated, Wide Bandgap Materials Group, 20 Chapin Rd., Suite 1005, Pine Brook, NJ, 07058, United States
Ilya Zwieback
Affiliation:
izwieback@ii-vi.com, II-VI Incorporated, Wide Bandgap Materials Group, 20 Chapin Rd., Suite 1005, Pine Brook, NJ, 07058, United States
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Abstract

SiC single crystal wafers grown by sublimation exhibit relatively high dislocation densities. While it is generally known that the overall dislocation density tends to decrease throughout crystal growth, there has been a limited quantitative analysis of such trend. In this study, we measured the density of threading dislocations in the wafers sliced from several SiC boules. Although the dislocation density in the wafers sliced from different boules could differ by orders of magnitude, a consistent empirical relationship was found between the dislocation density (ρ) and the axial wafer position within the crystal (w): ρ is proportional to w(−0.5).

Monte Carlo simulations were performed based on two assumptions: (i) during growth the threading dislocations move randomly in the lateral directions, and (ii) two dislocations of opposite sign annihilate when they come within a critical distance between them. Good agreement was achieved between the model and experimental results. The critical distance determined from the simulations was in the range between a few hundred Ă and a micron.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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References

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