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

doi:10.1016/j.spmi.2014.10.031

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

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

13 Citations (Scopus)

Abstract

Schottky barrier height (SBH; Φ_B) and their dependence on the work function of metals (Φ_M) 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 (dΦ_B/dΦ_M) 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 language	English
Pages (from-to)	76-81
Number of pages	6
Journal	Superlattices and Microstructures
Volume	77
DOIs	https://doi.org/10.1016/j.spmi.2014.10.031
Publication status	Published - 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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title = "Investigation of Fermi level pinning at semipolar (11-22) p-type GaN surfaces",

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.",

keywords = "Barrier inhomogeneity model, Schottky contacts, Semipolar GaN, Surface states",

author = "Choi, {Young Yun} and Seongjun Kim and Munsik Oh and Hyunsoo Kim and Seong, {Tae Yeon}",

year = "2015",

month = mar,

doi = "10.1016/j.spmi.2014.10.031",

language = "English",

volume = "77",

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journal = "Superlattices and Microstructures",

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T1 - Investigation of Fermi level pinning at semipolar (11-22) p-type GaN surfaces

AU - Choi, Young Yun

AU - Kim, Seongjun

AU - Oh, Munsik

AU - Kim, Hyunsoo

AU - Seong, Tae Yeon

PY - 2015/3

Y1 - 2015/3

N2 - 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.

AB - 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.

KW - Barrier inhomogeneity model

KW - Schottky contacts

KW - Semipolar GaN

KW - Surface states

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