Theoretical investigation of atomic and electronic structures of Ga(2)O(3)(ZnO)(6)

J L F Da Silva, Aron Walsh, S H Wei

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Transparent conducting oxides (TCO) are widely used in technological applications ranging from photovoltaics to thin-film transparent field-effect transistors. In this work we report a first-principles investigation, based on density-functional theory, of the atomic and electronic properties of Ga(2)O(3)(ZnO)(6) (GZO(6)), which is a promising candidate to be used as host oxide for wide band gap TCO applications. We identify a low-energy configuration for the coherent distribution of the Ga and Zn atoms in the cation positions within the experimentally reported orthorhombic GZO(6) structure. Four Ga atoms are located in four-fold sites, while the remaining 12 Ga atoms in the unit cell form four shared Ga agglomerates (a motif of four atoms). The Zn atoms are distributed in the remaining cation sites with effective coordination numbers from 3.90 to 4.50. Furthermore, we identify the natural formation of twin-boundaries in GZO(6), which can explain the zigzag modulations observed experimentally by high-resolution transmission electron microscopy in GZO(n) (n=9). Due to the intrinsic twin-boundary formation, polarity inversion in the ZnO tetrahedrons is present which is facilitated by the formation of the Ga agglomerates. Our analysis shows that the formation of fourfold Ga sites and Ga agglomerates are stabilized by the electronic octet rule, while the distribution of Ga atoms and the formation of the twin-boundary help alleviate excess strain. Finally we identify that the electronic properties of GZO(6) are essentially determined by the electronic properties of ZnO, i.e., there are slight changes in the band gap and optical absorption properties.
Original languageEnglish
Article number214118
JournalPhysical Review B
Volume80
Issue number21
DOIs
Publication statusPublished - 2009

Fingerprint

Crystal atomic structure
atomic structure
Electronic structure
electronic structure
Atoms
Electronic properties
Oxides
atoms
electronics
oxides
Cations
Energy gap
Positive ions
cations
conduction
octets
Field effect transistors
High resolution transmission electron microscopy
coordination number
tetrahedrons

Keywords

  • optical-properties
  • electronic density of states
  • gallium compounds
  • crystal structure
  • photovoltaic cells
  • crystal-structure
  • phase-relationships
  • homologous
  • transmission electron microscopy
  • energy gap
  • compounds
  • density functional theory
  • transparent conducting oxides
  • wide band gap semiconductors
  • room-temperature
  • augmented-wave method
  • ab initio calculations
  • absorption coefficients
  • system
  • thin-films
  • semiconductors
  • film transistors
  • field effect transistors
  • thin
  • twin boundaries

Cite this

Theoretical investigation of atomic and electronic structures of Ga(2)O(3)(ZnO)(6). / Da Silva, J L F; Walsh, Aron; Wei, S H.

In: Physical Review B, Vol. 80, No. 21, 214118, 2009.

Research output: Contribution to journalArticle

Da Silva, J L F ; Walsh, Aron ; Wei, S H. / Theoretical investigation of atomic and electronic structures of Ga(2)O(3)(ZnO)(6). In: Physical Review B. 2009 ; Vol. 80, No. 21.
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AU - Da Silva, J L F

AU - Walsh, Aron

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N2 - Transparent conducting oxides (TCO) are widely used in technological applications ranging from photovoltaics to thin-film transparent field-effect transistors. In this work we report a first-principles investigation, based on density-functional theory, of the atomic and electronic properties of Ga(2)O(3)(ZnO)(6) (GZO(6)), which is a promising candidate to be used as host oxide for wide band gap TCO applications. We identify a low-energy configuration for the coherent distribution of the Ga and Zn atoms in the cation positions within the experimentally reported orthorhombic GZO(6) structure. Four Ga atoms are located in four-fold sites, while the remaining 12 Ga atoms in the unit cell form four shared Ga agglomerates (a motif of four atoms). The Zn atoms are distributed in the remaining cation sites with effective coordination numbers from 3.90 to 4.50. Furthermore, we identify the natural formation of twin-boundaries in GZO(6), which can explain the zigzag modulations observed experimentally by high-resolution transmission electron microscopy in GZO(n) (n=9). Due to the intrinsic twin-boundary formation, polarity inversion in the ZnO tetrahedrons is present which is facilitated by the formation of the Ga agglomerates. Our analysis shows that the formation of fourfold Ga sites and Ga agglomerates are stabilized by the electronic octet rule, while the distribution of Ga atoms and the formation of the twin-boundary help alleviate excess strain. Finally we identify that the electronic properties of GZO(6) are essentially determined by the electronic properties of ZnO, i.e., there are slight changes in the band gap and optical absorption properties.

AB - Transparent conducting oxides (TCO) are widely used in technological applications ranging from photovoltaics to thin-film transparent field-effect transistors. In this work we report a first-principles investigation, based on density-functional theory, of the atomic and electronic properties of Ga(2)O(3)(ZnO)(6) (GZO(6)), which is a promising candidate to be used as host oxide for wide band gap TCO applications. We identify a low-energy configuration for the coherent distribution of the Ga and Zn atoms in the cation positions within the experimentally reported orthorhombic GZO(6) structure. Four Ga atoms are located in four-fold sites, while the remaining 12 Ga atoms in the unit cell form four shared Ga agglomerates (a motif of four atoms). The Zn atoms are distributed in the remaining cation sites with effective coordination numbers from 3.90 to 4.50. Furthermore, we identify the natural formation of twin-boundaries in GZO(6), which can explain the zigzag modulations observed experimentally by high-resolution transmission electron microscopy in GZO(n) (n=9). Due to the intrinsic twin-boundary formation, polarity inversion in the ZnO tetrahedrons is present which is facilitated by the formation of the Ga agglomerates. Our analysis shows that the formation of fourfold Ga sites and Ga agglomerates are stabilized by the electronic octet rule, while the distribution of Ga atoms and the formation of the twin-boundary help alleviate excess strain. Finally we identify that the electronic properties of GZO(6) are essentially determined by the electronic properties of ZnO, i.e., there are slight changes in the band gap and optical absorption properties.

KW - optical-properties

KW - electronic density of states

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KW - crystal-structure

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KW - homologous

KW - transmission electron microscopy

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KW - thin-films

KW - semiconductors

KW - film transistors

KW - field effect transistors

KW - thin

KW - twin boundaries

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