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Title: Distribution of cations in wurtzitic In xGa 1-xN and In xAl 1-xN alloys: Consequences for energetics and quasiparticle electronic structures

The ternary, isostructural, wurtzite-derived group-III mononitride alloys In xGa 1-xN andIn xAl 1-xN are reexamined within a cluster expansion approach. Using density functional theory together with the AM05 exchange-correlation functional, the total energies and the optimized atomic geometries of all 22 clusters classes of the cluster expansion for each material system are calculated. The computationally demanding calculation of the corresponding quasiparticle electronic structures is achieved for all cluster classes by means of a recently developed scheme to approximately solve the quasiparticle equation based on the HSE06 hybrid functional and the G₀W₀ approach. Using two different alloy statistics, the configurational averages for the lattice parameters, the mixing enthalpies, and the bulk moduli are calculated. The composition-dependent electronic structures of the alloys are discussed based on configurationally averaged electronic states, band gaps, and densities of states. Ordered cluster arrangements are found to be energetically rather unfavorable, however, they possess the smallest energy gaps and, hence, contribute to light emission. The influence of the alloy statistics on the composition dependencies and the corresponding bowing parameters of the band gaps is found to be significant and should, hence, lead to different signatures in the optical-absorption or -emission spectra.
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Publication Date:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 85; Journal Issue: 11; Related Information: CHORUS Timestamp: 2017-06-20 12:15:33; Journal ID: ISSN 1098-0121
American Physical Society
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier: