Electronic Structure and Spontaneous Polarization in Sc_xAl_yGa_1-x-yN Alloys Lattice-Matched to GaN: A First-Principles Study

• Kazuhiro Shimada

• Shigefusa F. Chichibu

• Masahiro Hata

• Hiroyuki Sazawa

• Tomoyuki Takada

• Takayuki Sota

抄録

We performed first-principles calculations of the spontaneous polarization and electronic band structures in Sc x Al y Ga 1- x - y N alloys assuming their growth on freestanding GaN. We found an apparent deviation from the Vegard's law of the lattice constants of the Sc x Al y Ga 1- x - y N alloys lattice-matched to GaN. It was supposed that this deviation comes from the different bonding properties of IIIB and IIIA nitrides, resulting in different crystal structures, such as hexagonal and wurtzite structures. As was reported in our previous report on Y x Al y Ga 1- x - y N [K. Shimada et al.: J. Appl. Phys. 110 (2011) 074114], we also found that in Sc x Al y Ga 1- x - y N alloys, the superlattice-like structure of Sc atoms reduced the magnitude of spontaneous polarization [K. Shimada et al.: Semicond. Sci. Technol. 27 (2012) 105014]. The magnitude of the spontaneous polarization of Sc x Al y Ga 1- x - y N is larger than that of Y x Al y Ga 1- x - y N in a wide mole fraction range of Ga. We found the nonlinearity and dependence of the atomic arrangement of Sc in the alloys. The band-gap energies at Γ have the same characteristics as the spontaneous polarization. The band-gap energies of Sc x Al y Ga 1- x - y N are also larger than those of Y x Al y Ga 1- x - y N in the wide mole fraction range of Ga. The band structures of Sc x Al y Ga 1- x - y N have a direct gap at Γ and form a flat band around the valence band top originating from the hybridization of the Sc 3d and N 2p electrons.

収録刊行物

• Japanese Journal of Applied Physics

  Japanese Journal of Applied Physics 52 (8S), 08JM04-, 2013-06-20

  IOP Publishing

キーワード

• General Physics and Astronomy
• General Engineering

詳細情報

• CRID: 1360847874817766912
• NII論文ID: 210000142746
• DOI: 10.7567/jjap.52.08jm04
• ISSN: 13474065
• ISSN: 00214922
• Web Site: https://iopscience.iop.org/article/10.7567/JJAP.52.08JM04
• Web Site: https://iopscience.iop.org/article/10.7567/JJAP.52.08JM04/pdf
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