Special Quasi-ordered Structures: role of short-range order in the semiconductor alloy (GaN)\(_{1-x}\)(ZnO)\(_x\)

This paper studies short-range order (SRO) in the semiconductor alloy (GaN)\(_{1-x}\)(ZnO)\(_x\). Monte Carlo simulations performed on a density functional theory (DFT)-based cluster expansion model show that the heterovalent alloys exhibit strong SRO because of the energetic preference for the vale...

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Bibliographic Details
Published in:arXiv.org 2015-12
Main Authors: Liu, Jian, Fernández-Serra, Maria V, Allen, Philip B
Format: Article
Language:English
Subjects:
Alloy development
Alloys
Bonding strength
Bowing
Computer simulation
Density functional theory
Gallium nitrides
Intermetallic compounds
Lattice vibration
Short range order
Zinc oxide
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Summary:This paper studies short-range order (SRO) in the semiconductor alloy (GaN)\(_{1-x}\)(ZnO)\(_x\). Monte Carlo simulations performed on a density functional theory (DFT)-based cluster expansion model show that the heterovalent alloys exhibit strong SRO because of the energetic preference for the valence-matched nearest-neighbor Ga-N and Zn-O pairs. To represent the SRO-related structural correlations, we introduce the concept of Special Quasi-ordered Structure (SQoS). Subsequent DFT calculations reveal dramatic influence of SRO on the atomic, electronic and vibrational properties of the (GaN)\(_{1-x}\)(ZnO)\(_x\) alloy. Due to the enhanced statistical presence of the energetically unfavored Zn-N bonds with the strong Zn3\(d\)-N2\(p\) repulsion, the disordered alloys exhibit much larger lattice bowing and band-gap reduction than those of the short-range ordered alloys. Inclusion of lattice vibrations stabilizes the disordered alloy.
ISSN:2331-8422
DOI:10.48550/arxiv.1505.06329