Interface analysis of Ti/Al/Ti/Au ohmic contacts with regrown n +-GaN layers using molecular beam epitaxy

Hui Chan Seo, Shankar Sivaramakrishnan, Jian Min Zuo, Liang Pang, Philip T. Krein, Kyekyoon Kim

Research output: Contribution to journalArticlepeer-review

Abstract

The regrowth technique of highly doped n-type GaN layers is reliable and effective for lowering the ohmic contact resistance. The interface between metal contacts with Ti/Al/Ti/Au and regrown n+-GaN/GaN layers were analyzed in detail with transmission electron microscopy. During the annealing process, Ti metals and N atoms diffusing from GaN layers formed TiN epitaxial layers between metal alloys and n+-GaN layers. The orientational relationship between GaN and TiN was [1 0 0]GaN//[-1 1 0] TiN verified by nano-beam diffraction. Al atoms diffused through the GaN layers and formed thin AlGaN phase. Al content was confirmed as 60% by high-resolution transmission electron microscopy images. Electron energy loss spectroscopy showed that Si dopants were confined within n+-GaN layers. These results show that in regrowth technique both TiN layers and Si dopants affect the contact properties because the formation of TiN layers can induce nitrogen vacancies from GaN, while Si-doped GaN layers can enhance the tunneling effect through the metal contacts resulting in reduced contact resistance.

Original languageEnglish (US)
Pages (from-to)1627-1631
Number of pages5
JournalSurface and Interface Analysis
Volume43
Issue number13
DOIs
StatePublished - Dec 2011

Keywords

  • GaN
  • interface
  • ohmic contact

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Chemistry
  • Surfaces, Coatings and Films

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