Ultralow-contact-resistance au-free ohmic contacts with low annealing temperature on AlGaN/GaN heterostructures

Jinhan Zhang, Xuanwu Kang, Xinhua Wang, Sen Huang, Chen Chen, Ke Wei, Yingkui Zheng, Qi Zhou, Wanjun Chen, Bo Zhang, Xinyu Liu

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

We report on the electrical and microstructural characterization of Au-free Ti/Al/Ti/TiN contacts for AlGaN/GaN heterostructures. Ultra-low Au-free ohmic contact has been obtained with contact resistance and specific contact resistivity as low as 0.21Ω mm and 1.16 × 10-6 Ω cm2, respectively. The ohmic alloy temperature is reduced as low as 550 °C by pre-ohmic recess of the AlGaN barrier and optimization of the thickness of bottom Ti layer. We found that interfacial layer formation of AlN between the ohmic metal and AlGaN surface is crucial to realize a low contact resistance with reduced low annealing temperature by a combination of electrical I-V characterization and high-resolution transmission electron microscopy analysis. Furthermore, we suggest a hypothesis that the bottom Ti layer plays a catalytic role for the Al-N reaction with optimized thickness.

Original languageEnglish (US)
Pages (from-to)847-850
Number of pages4
JournalIEEE Electron Device Letters
Volume39
Issue number6
DOIs
StatePublished - Jun 2018

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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