Investigation of Fermi level pinning at semipolar (11-22) p-type GaN surfaces

Young Yun Choi, Seongjun Kim, Munsik Oh, Hyunsoo Kim, Tae Yeon Seong

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Schottky barrier height (SBH; ΦB) and their dependence on the work function of metals (ΦM) at semipolar (11-22) p-GaN surfaces were investigated using Schottky diodes fabricated with different metals. The SBH increased with temperature, whereas the ideality factor decreased. This behavior was explained by means of the barrier inhomogeneity model, giving the mean barrier heights of 1.93-2.05 eV for different metals. The S-parameter (dΦB/dΦM) was obtained to be 0.04. This small S-parameter implies that the surface Fermi level is nearly perfectly pinned at deep-level states (caused by vacancy-related and/or Mg-induced defects) located at 1.98 eV above the valence band. This finding indicates that the surface modification is essentially required for the formation of high-quality ohmic and/or Schottky contacts.

Original languageEnglish
Pages (from-to)76-81
Number of pages6
JournalSuperlattices and Microstructures
Volume77
DOIs
Publication statusPublished - 2015 Mar

Keywords

  • Barrier inhomogeneity model
  • Schottky contacts
  • Semipolar GaN
  • Surface states

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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