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Annealing Study of Ga Implanted p-Type 6H-SiC for Ohmic Contact Metallizations

Published online by Cambridge University Press:  21 March 2011

M. Prenatt
Affiliation:
Electrical and Computer Engineering Department, University of Maryland, College Park, Maryland 20742 Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783
A. A. Iliadis
Affiliation:
Electrical and Computer Engineering Department, University of Maryland, College Park, Maryland 20742
R. D. Vispute
Affiliation:
Center for Superconductivity Research, Physics Department, University of Maryland, College Park, Maryland 20742
M. C. Wood
Affiliation:
Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783
M. Derenge
Affiliation:
Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783
B. Geil
Affiliation:
Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783
K. A. Jones
Affiliation:
Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783
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Abstract

Shallow implantations of Ga ions were performed on p-type 6H-SiC by conventional broad area implantation, and the physical and electrical properties of the Ga-SiC system upon high temperature annealing were examined, in order to understand the role of Ga in ohmic contact formation. The shallow implantation depth (30 nm) and high Ga doses ranging between 1×1015 and 1×1016 cm−2, resulted in heavy surface damage as observed by atomic force microscopy surveys. Samples annealed using a sacrificial SiC wafer as a capping layer, showed no improvement in surface roughness for annealing up to 1300 °C, while at 1500 °C, surface roughness was markedly changed. At 1600 °C the surface re-crystallized back to the stepped terraced morphology of the un-implanted surface but with significantly larger step and terrace size. At this annealing temperature, heavy Ga loss from the surface was observed. Samples annealed at 1500 °C using an AlN capping layer, showed significant outdiffusion of Si into the AlN layer, and redistribution of Ga within the SiC surface. The contact resistance of as-implanted and annealed samples using the sacrificial SiC wafer, were measured by the TLM method. Although contact resistance was found to decrease with increasing annealing temperature, sheet resistance increased, and contact resistance values were higher than expected, indicating that the heavy loss of Ga atoms contributed to the increased levels of contact resistance.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

REFERENCES

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