The origins of leaky characteristics of Schottky diodes on p-GaN

L. S. Yu, L. Jia, D. Qiao, S. S. Lau, J. Li, J. Y. Lin, H. X. Jiang

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The possible origins of leaky characteristics of Schottky barrier on p-GaN have been investigated. The as-grown samples did not show any electrical activities using Hall measurements. Ni diodes made on as-activated samples, either at 950 °C for 5 s or at 750 °C for 5 min exhibited quasiohmic behavior. Upon sequential etching of the sample to remove a surface layer of 150 Å, 1200 Å, and 5000 Å from the sample, the I-V behavior became rectifying. I-V-T measurements showed that the slopes of the lnI-V curves were independent of the temperature, indicative of a prominent component of carrier tunneling across the Schottky junction. C-V measurements at each etch-depth indicated a decreasing acceptor concentration from the surface. The highly doped (>1.7 × 1019 cm-3) and defective surface region (within the top 150 Å from surface) rendered the as-activated Schottky diodes quasiohmic in their I-V characteristics. The leaky I-V characteristics, often reported in the literature, was likely to be originated from the surface layer, which gives rise to carrier tunneling across the Schottky barrier. This highly doped/defective surface region, however, can play an important role in ohmic contact formation on p-GaN.

Original languageEnglish
Pages (from-to)292-296
Number of pages5
JournalIEEE Transactions on Electron Devices
Issue number2
StatePublished - Feb 2003


  • Doping
  • Schottky barriers
  • Surface
  • Tunneling
  • p-GaN


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