Low-Resistivity V/Al/Mo/Au Ohmic Contacts on AlGaN/GaN Annealed at Low Temperatures

We investigated the electrical characteristics of V/Al/Mo/Au ohmic contacts on AlGaN/GaN heterostructure field effect transistors (HFETs). A minimum ohmic contact resistivity of $1.6\times 10^{-6}$ $\Omega$ cm 2 was achieved after annealing at 550 \mbox{ \circ C} by optimizing V thickness to 15 nm....

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2010-04, Vol.49 (4), p.04DF10-04DF10-4
Main Authors: Yafune, Norimasa, Nagamori, Motoi, Chikaoka, Hironari, Watanabe, Fuminao, Sakuno, Keiichi, Kuzuhara, Masaaki
Format: Article
Language:English
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Summary:We investigated the electrical characteristics of V/Al/Mo/Au ohmic contacts on AlGaN/GaN heterostructure field effect transistors (HFETs). A minimum ohmic contact resistivity of $1.6\times 10^{-6}$ $\Omega$ cm 2 was achieved after annealing at 550 \mbox{ \circ C} by optimizing V thickness to 15 nm. Cross-sectional transmission electron microscope (TEM) images exhibited a large difference in the extent of metal reaction between V/Al/Mo/Au and Ti/Al/Mo/Au. In addition to their lower contact resistivities, the low-temperature annealed V/Al/Mo/Au ohmic contacts exhibited better characteristics, such as enhanced breakdown voltages by about 100 V and smooth surface morphology, than the Ti/Al/Mo/Au ohmic contact annealed at the optimum annealing temperature.
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.49.04DF10