Microstructure of Ti/Al ohmic contacts for n-AlGaN

Transmission electron microscopy was employed to evaluate the microstructure of Al/Ti ohmic contacts to AlGaN/GaN heterostructure field-effect transistor structures. Contact resistance was found to depend on the structure and composition of the metal and AlGaN layers, and on atomic structure of the...

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Bibliographic Details
Published in:Applied physics letters 1998-11, Vol.73 (18), p.2582-2584
Main Authors: Ruvimov, S., Liliental-Weber, Z., Washburn, J., Qiao, D., Lau, S. S., Chu, Paul K.
Format: Article
Language:English
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Summary:Transmission electron microscopy was employed to evaluate the microstructure of Al/Ti ohmic contacts to AlGaN/GaN heterostructure field-effect transistor structures. Contact resistance was found to depend on the structure and composition of the metal and AlGaN layers, and on atomic structure of the interface. A 15–25-nm-thick interfacial AlTi2N layer was observed at the contact-AlGaN interface. Formation of such nitrogen-containing layers appears to be essential for ohmic behavior on n-type III-nitride materials suggesting a tunneling contact mechanism. Contact resistivity was found to increase with Al fraction in the AlGaN layer.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.122512