Lattice Distortion Analysis of Nonpolar a-plane (11¯20) GaN Films by Using a Grazing-Incidence X-Ray Diffraction Technique
- 주제(키워드) Nonpolar , a-plane , GaN , Anisotropy , X-ray diffraction
- 발행기관 한국물리학회
- 발행년도 2015
- 총서유형 Journal
- KCI ID ART001965720
- 본문언어 영어
초록/요약
This work examines the anisotropic microstructure and the lattice distortions of nonpolar a-plane(11¯20) 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-rayin-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 SiNxinterlayers. Analysis revealed the peak widths of the XRCs displayed an isotropic behavior for anonpolar a-GaN bulk crystal. Thus, the in-plane anisotropy of the XRC peak widths for nonpolara-GaN films apparently originates from the heteroepitaxial growth of the a-GaN layer on a foreignsubstrate. The lattice distortion analysis identified the presence of compressive strains in both thetwo in-plane directions (the c- and the m-axis), as well as a tensile strain along the normal growthdirection. In addition, the observed frequency shifts in the Raman E2 (high) mode for the a-GaNfilms showed the existence of considerable in-plane compressive strain on both a-GaN films, asconfirmed by the lattice distortion analysis performed using the grazing-incidence XRD method.
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