Microstructure of Ti/Al ohmic contacts for n-AlGaN
- Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- University of California, San Diego, La Jolla, California 92093 (United States)
- City University of Hong Kong (Hong Kong)
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{endash}25-nm-thick interfacial AlTi{sub 2}N layer was observed at the contact-AlGaN interface. Formation of such nitrogen-containing layers appears to be essential for ohmic behavior on {ital n}-type III-nitride materials suggesting a tunneling contact mechanism. Contact resistivity was found to increase with Al fraction in the AlGaN layer. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 663665
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 18 Vol. 73; ISSN 0003-6951; ISSN APPLAB
- Country of Publication:
- United States
- Language:
- English
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