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In-Based Ohmic Contacts to the Base Layer of GaAs-AlGaAs Heterojunction Bipolar Transistors

Published online by Cambridge University Press:  25 February 2011

F. Ren ,
S. J. Pearton ,
W. S. Hobson ,
T. R. Fullowan ,
A. B. Emerson ,
A. W. Yanof  and
D. M. Schleich
F. Ren
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ 07974
S. J. Pearton
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ 07974
W. S. Hobson
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ 07974
T. R. Fullowan
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ 07974
A. B. Emerson
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ 07974
A. W. Yanof
Affiliation:
AT&T Bell Laboratories, Murray Hill, NJ 07974
D. M. Schleich
Affiliation:
Polytechnic University, Brooklyn, NY
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Abstract

The use of AuBe-In/Ag/Au p-ohmic contacts for the base layer of GaAs-AIGaAs heterojunction bipolar transistors (HBTs) is described. Annealing at 420°C for 20 sec produces a contact resistivity of 0.095 Ω mm and a specific contact resistance of l.5 × 10-7 Ω cm2, and the surface morphology of the contact is excellent. The role of the silver is as a diffusion barrier to prevent Au spiking into the base layer which could degrade the HBT performance. The presence of the In layer is highly desirable in order to reduce the contact resistance, probably by forming an InGaAs phase at the metal-GaAs interface. Beryllium acts as the p-type dopant, and the top Au layer is used to lower the contact sheet resistance. Current transport through the structure is dominated by tunneling through the barrier due to field emission in the highly doped base layer at p-type doping levels above ∼1019 cm−3

Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 181: Symposium B – Advanced Metallizations in Microelectronics , 1990 , 481
Copyright
Copyright © Materials Research Society 1990

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References

REFERENCES

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