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Ta-based interface ohmic contacts to AlGaNGaN heterostructures L. Jia, L. S. Yu, P. M. Asbeck, and S. S. Lau

Summary: Ta-based interface ohmic contacts to AlGaNĠGaN heterostructures
D. Qiao,a)
L. Jia, L. S. Yu, P. M. Asbeck, and S. S. Lau
University of California, San Diego, La Jolla, California 92093
S.-H. Lim and Z. Liliental-Weber
Lawrence Berkeley National Laboratory, Berkeley, California 94720
T. E. Haynes
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
J. B. Barner
Jet Propulsion Laboratory, Pasadena, California 91109
Received 12 January 2001; accepted for publication 21 February 2001
Al/Ti based metallization is commonly used for ohmic contacts to n-GaN and related compounds.
We have previously reported an ohmic contact scheme specially designed for AlGaN/GaN
heterostructure field-effect transistors HFETs D. Qiao et al., Appl. Phys. Lett. 74, 2652 1999 .
This scheme, referred to as the ``advancing interface'' contact, takes advantage of the interfacial
reactions between the metal layers and the AlGaN barrier layer in the HFET structure. These
reactions consume a portion of the barrier, thus facilitating carrier tunneling from the source/drain
regions to the channel region. The advancing interface approach has led to consistently low contact
resistance on Al0.25Ga0.75N/GaN HFETs. There are two drawbacks of the Al/Ti based advancing
interface scheme, i it requires a capping layer for the ohmic formation annealing since Ti is too


Source: Asbeck, Peter M. - Department of Electrical and Computer Engineering, University of California at San Diego


Collections: Engineering