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A Study of Defects and Surface Properties in AlGaN/GaN High Electron Mobility Transistors (HEMTs) Grown by MOCVD on Semi-Insulating SiC Substrates

Published online by Cambridge University Press:  01 February 2011

Yongkun Sin ,
Hyun I Kim ,
Paul Adams  and
Gary Stupian
Yongkun Sin
Affiliation:
yongkun.sin@aero.org, The Aerospace Corporation, Electronics and Photonics Laboratory, 2350 E El Segundo Bl., El Segundo, CA, 90245, United States
Hyun I Kim
Affiliation:
Hyun.I.Kim@aero.org, The Aerospace Corporation, Space Materials Laboratory, El Segundo, CA, 90245, United States
Paul Adams
Affiliation:
paul.adams@aero.org, The Aerospace Corporation, Space Materials Laboratory, El Segundo, CA, 90245, United States
Gary Stupian
Affiliation:
gary.stupian@aero.org, The Aerospace Corporation, Electronics and Photonics Laboratory, El Segundo, CA, 90245, United States
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Abstract

AlGaN/GaN HEMTs (High Electron Mobility Transistors) grown on semi-insulating (SI) SiC substrates are very promising for high power, high speed, and high temperature operation with great potential for both military and commercial applications. These high performance characteristics are possible due to presence of high two-dimensional electron gas (2 DEG) charge sheet density maintaining a high Hall mobility at the AlGaN barrier/GaN buffer hetero-interface. However, reliability of AlGaN HEMTs still remains a major concern because of the large number of defects and traps present both in the bulk as well as at the surface leading to current collapse. We report on the study of defects and surface properties in MOCVD-grown Al0.27Ga0.73N HEMT structures on SI SiC substrates. Our HEMT structures consist of a 25nm thick undoped AlGaN barrier layer and a 3μm thick undoped GaN buffer layer grown on a 100nm thick AlN nucleation layer. Hall measurements showed a charge sheet density of ∼1013/cm2 and a Hall mobility of ∼1500cm2/V·sec. Both cross-sectional and plan view TEMs were employed to study defects in the heterostructures and XPS (X-ray Photoelectron Spectroscopy) and AES (Auger Electron Spectroscopy) employed to study surface properties in both GaN and AlGaN layers. DC characterization results from AlGaN Schottky diodes with Pt/Au Schottky contacts are also reported along with results from AlGaN/GaN HEMT devices.

Keywords

semiconductingdefectssurface chemistry
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 955: Symposium I – Advances in III-V Nitride Semiconductor Materials and Devices , 2006 , 0955-I11-02
Copyright
Copyright © Materials Research Society 2007

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References

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