Lattice distortion analysis of nonpolar a-plane $$(11\bar 20)$$ GaN films by using a grazing-incidence X-ray diffraction technique

Yong Gon Seo, Jihoon Kim, Sung Min Hwang, Ji Hyun Kim, Soohwan Jang, Heesan Kim, Kwang Hyeon Baik

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This work examines the anisotropic microstructure and the lattice distortions of nonpolar a-plane (Formula Presented.) GaN (a-GaN) films by using the grazing-incidence X-ray diffraction technique. Faulted a-GaN films typically exhibit an in-plane anisotropy of the structural properties along the X-ray in-beam directions. For this reason, the anisotropic peak broadenings of the X-ray rocking curves (XRCs) were observed for various angle (phi) rotations for a-GaN films with and without SiNx interlayers. Analysis revealed the peak widths of the XRCs displayed an isotropic behavior for a nonpolar a-GaN bulk crystal. Thus, the in-plane anisotropy of the XRC peak widths for nonpolar a-GaN films apparently originates from the heteroepitaxial growth of the a-GaN layer on a foreign substrate. The lattice distortion analysis identified the presence of compressive strains in both the two in-plane directions (the c- and the m-axis), as well as a tensile strain along the normal growth direction. In addition, the observed frequency shifts in the Raman E2 (high) mode for the a-GaN films showed the existence of considerable in-plane compressive strain on both a-GaN films, as confirmed by the lattice distortion analysis performed using the grazing-incidence XRD method.

Original languageEnglish
Pages (from-to)607-611
Number of pages5
JournalJournal of the Korean Physical Society
Volume66
Issue number4
DOIs
Publication statusPublished - 2015

Keywords

  • a-plane
  • Anisotropy
  • GaN
  • Nonpolar
  • X-ray diffraction

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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