Categorization of surface polarity from a crystallographic approach

Hinuma, Yoyo; Kumagai, Yu; Oba, Fumiyasu; Tanaka, Isao

doi:10.1016/j.commatsci.2015.11.042

Cited by 52 publications

(39 citation statements)

References 33 publications

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“…Our computed positions of the IIIa nitrides are very close to the values reported by Moses et al [57]. As expected, the VBM positions at the (100) and (110) surfaces are very close to each other as they belong to the Tasker type I surfaces [37,38,58]. The VBMs in ScN are relatively much higher even compared to that in InN with a similar band gap.…”

Section: B Band Alignmentsupporting

confidence: 89%

Point Defects and p -Type Doping in ScN from First Principles

2018

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Scandium nitride (ScN) has been intensively researched as a prototype of rocksalt nitrides and a potential counterpart of the wurtzite group IIIa nitrides. It also holds great promise for applications in various fields, including optoelectronics, thermoelectrics, spintronics, and piezoelectrics. We theoretically investigate the bulk properties, band-edge positions, chemical stability, and point defects, i.e., native defects, unintentionally doped impurities, and p-type dopants of ScN using the Heyd-Scuseria-Ernzerhof hybrid functional. We find several fascinating behaviors: (i) a high level for the valence-band maximum, (ii) the lowest formation energy among binary nitrides, (iii) high formation energies of native point defects, (iv) low formation energies of donor-type impurities, and (v) a p-type conversion by Mg doping. Furthermore, we uncover the origins of the Burstein-Moss shift commonly observed in ScN. Our work sheds light on a fundamental understanding of ScN in regard to its technological applications.

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Section: B Band Alignmentsupporting

confidence: 89%

Point Defects and p -Type Doping in ScN from First Principles

2018

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“…We use a combination of bulk and slab-vacuum models as typically done in the IP evaluation [25], the latter of which is for a β-Ga 2 O 3 (100) surface with 40 atoms and the slab and vacuum thickness over 20 Å and constructed on the basis of the procedure described in Ref. [96]. Since surface geometry optimization using the hybrid functional is computationally demanding, bulk and surface geometries are optimized using the PBEsol functional [97], which improves the lattice constants of β-Ga 2 O 3 over the standard PBE functional [98] and yields values closer to those of HSE(0.35, 0.21).…”

Section: (α μ)mentioning

confidence: 99%

First-principles study of self-trapped holes and acceptor impurities in Ga2O3 polymorphs

Gake

Kumagai

Oba

2019

Phys. Rev. Materials

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We investigate the stability of self-trapped holes (STHs) and the acceptor levels of substitutional Mg and N impurities in α-, β-, δ-, and ε-Ga 2 O 3 using first-principles calculations based on the hybrid functional approach to assess their p-type dopability. When Fock-exchange and screening parameter values in the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional are optimized to satisfy the generalized Koopmans' theorem for a STH level in β-Ga 2 O 3 , the band gap is slightly overestimated, while functionals that well reproduce the band gap show slight convex behavior against the fractional electron number. However, the absolute position of the STH level at a fixed geometry is nearly independent of the parameter value, showing that the results are robust as long as the STH geometry and localized electronic nature are appropriately described and the band edges are well reproduced. In all of the polymorphs, holes localize with high self-trapping energies rather than being delocalized. Furthermore, both Mg and N impurities introduce polaronic acceptor states, and their acceptor levels lie far above the valence band maximum in all the polymorphs. Thus, the p-type doping of the four Ga 2 O 3 polymorphs seems unfeasible in terms of the STH formation and the related deep, polaronic acceptor nature of the Mg and N impurities.

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“…In combination with the automated generation of surface and interface simulation models (e.g., Ref. [49]), non-self-consistent hybrid functional calculations would allow us to do systematic study or high-throughput screening based on the band alignment.…”

Section: A Dielectric-dependent Hybrid Functionalsmentioning

confidence: 99%

“…The origin of the energy is set at the valence band maximum. Band paths reported in Ref [62]. are used.…”

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confidence: 99%

Band alignment of semiconductors and insulators using dielectric-dependent hybrid functionals: Toward high-throughput evaluation

et al. 2017

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The band alignment of prototypical semiconductors and insulators is investigated using first-principles calculations. A dielectric-dependent hybrid functional, where the non-local Fock exchange mixing is set at the reciprocal of the static electronic dielectric constant and the exchange-correlation is otherwise treated as in the Perdew-Burke-Ernzerhof (PBE0) hybrid functional, is used as well as the Heyd-Scuseria-Ernzerhof (HSE06) hybrid and PBE semilocal functionals. In addition, these hybrid functionals are applied non-self-consistently to accelerate calculations. The systems considered include C and Si in the diamond structure, BN, AlP, AlAs, AlSb, GaP, GaAs, InP, ZnS, ZnSe, ZnTe, CdS, CdSe, and CdTe in the zinc-blende structure, MgO in the rocksalt structure, and GaN and ZnO in the wurtzite structure. Surface band positions with respect to the vacuum level, i.e. ionization potentials and electron affinities, and band offsets at selected zinc-blende heterointerfaces are evaluated as well as band gaps. The non-self-consistent approach speeds up hybrid functional calculations by an order of magnitude, while it is shown using HSE06 that the resultant band gaps and surface band positions are similar to the self-consistent results. The dielectric-dependent hybrid functional improves the band gaps and surface band positions of wide-gap systems over HSE06. The interfacial band offsets are predicted with a similar degree of precision. Overall, the performance of the dielectric-dependent hybrid functional is comparable to the GW 0 approximation based on many-body perturbation theory in the prediction of band gaps and alignments for most systems. The present results demonstrate that the dielectric-dependent hybrid functional, particularly when applied non-self-consistently, is promising for applications to systematic calculations or high-throughput screening that demand both computational efficiency and sufficient accuracy.

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Categorization of surface polarity from a crystallographic approach

Cited by 52 publications

References 33 publications

Point Defects and p -Type Doping in ScN from First Principles

Point Defects and p -Type Doping in ScN from First Principles

First-principles study of self-trapped holes and acceptor impurities in Ga2O3 polymorphs

Band alignment of semiconductors and insulators using dielectric-dependent hybrid functionals: Toward high-throughput evaluation

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