Effects of hydrogen treatment on ohmic contacts to p-type GaN films

Bohr Ran Huang*, Chia Hui Chou, Wen Cheng Ke, Yi Lun Chou, Chia Lung Tsai, Meng Chyi Wu

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

6 Scopus citations

Abstract

This study investigated the effects of hydrogen (H 2 ) treatment on metal contacts to Mg-doped p-GaN films by Hall-effect measurement, current-voltage (I-V) analyzer and X-ray photoemission spectra (XPS). The interfacial oxide layer on the p-GaN surface was found to be the main reason for causing the nonlinear I-V behavior of the untreated p-GaN films. The increased nitrogen vacancy (V N ) density due to increased GaN decomposition rate at higherature hydrogen treatment is believed to form high density surface states on the surface of p-GaN films. Compared to untreated p-GaN films, the surface Fermi level determined by the Ga 2p core-level peak on 1000 °C H 2 -treated p-GaN films lies about ∼2.1 eV closer to the conduction band edge (i.e., the surface inverted to n-type behavior). The reduction in barrier height due to the high surface state density pinned the surface Fermi level close to the conduction band edge, and allowed the electrons to easily flow over the barrier from the metal into the p-GaN films. Thus, a good ohmic contact was achieved on the p-GaN films by the surface inversion method.

Original languageEnglish
Pages (from-to)7490-7493
Number of pages4
JournalApplied Surface Science
Volume257
Issue number17
DOIs
StatePublished - 15 06 2011

Keywords

  • Hydrogen
  • Inversion
  • Ohmic contact
  • P-GaN film
  • XPS

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