Dislocation-induced nonuniform interfacial reactions of Ti/Al/Mo/Au ohmic contacts on AlGaN/GaN heterostructure

Liang Wang, Fitih M. Mohammed, Ilesanmi Adesida

Research output: Contribution to journalArticlepeer-review


Transmission electron microscopy (TEM) is utilized to elucidate the postannealing interfacial microstructure of TiAlMoAu metallization with AlGaNGaN heterostructures to gain insight into the formation mechanism of low-resistance ohmic contacts. The reaction between the metal and the AlGaN layer does not proceed uniformly. Localized penetration through the AlGaN layer beyond the two-dimensional electron gas (2DEG) is observed while partial consumption of the AlGaN layer is noted in other areas. Analytical TEM analyses confirm that the main reaction product is TiN. A correlation between the appearance of TiN islands and threading dislocations is observed. Threading dislocations serve as short-circuit diffusion channels, and are responsible for the nonuniform reaction. TiN islands have a large total area of intimate contact with the 2DEG, and since no tunneling of electron through the AlGaN is required, a low-resistance ohmic contact is obtained.

Original languageEnglish (US)
Article number141915
Pages (from-to)1-3
Number of pages3
JournalApplied Physics Letters
Issue number14
StatePublished - Oct 3 2005
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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