Nonalloyed ohmic contact formation in Ti/Al contacts to n-type AlGaN

Yow Jon Lin, Feng Tso Chien, Ching Ting Lee, Chi Shin Lin, Yang Chun Liu

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Abstract

Nonalloyed ohmic contact formation in Ti/Al contacts to n-type AlGaN (n-AlGaN) was achieved in this study. The surface chemistry and electrical properties of n-AlGaN surfaces were studied via x-ray photoelectron spectroscopy before and after oxidation and wet chemical treatments. The authors found that changes in the contact resistance are dominated by changes in the Al mole fraction and the interface states. Oxidation and HF and (NH4) 2Sx treatments on n-AlGaN led to an increase in the electron affinity (due to a reduction in the Al content at the n-AlGaN surface) and a reduction in the surface band bending (due to more N vacancies and N vacancies being occupied by S (i.e. donor-like states) than Al vacancies and Ga vacancies (i.e. acceptor-like states) near the n-AlGaN surface region), leading to the nonalloyed ohmic contact formation for the Al/Ti/n-AlGaN sample.

Original languageEnglish
Article number175105
JournalJournal of Physics D: Applied Physics
Volume41
Issue number17
DOIs
Publication statusPublished - 2008 Sep 7

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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