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

57 Citations (Scopus)

Abstract

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
Article number141915
Pages (from-to)1-3
Number of pages3
JournalApplied Physics Letters
Volume87
Issue number14
DOIs
Publication statusPublished - Oct 3 2005

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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