Quasiparticle self-consistent $GW$ band structures and high-pressure phase transitions of LiGaO${}_2$ and NaGaO$_2

Abstract

Quasi-particle self-consistent $GW$ calculations are presented for the band structures of LiGaO2 and NaGaO2 in the orthorhombic $Pna{2}_1$ tetrahedrally coordinated crystal structures. Symmetry labeling of the bands near the gap is carried out and effective mass tensors are extracted for the conduction band minimum and crystal field split valence band maxima at $\Gamma$. The gap is found to be direct at $\Gamma$ and is 5.81 eV in LiGaO2 and 5.46 eV in NaGaO2. Electron-phonon coupling zero-point normalization is estimated to lower these gaps by about 0.2 eV. Optical response functions are calculated within the independent particle long wavelength limit and show the expected anisotropy of the absorption onsets due to the crystal field splitting of the VBM. The results show that both materials are promising candidates as ultrawide gap semiconductors with wurtzite based tetrahedrally bonded crystal structures. Direct transitions from the lowest conduction band to higher bands, relevant to n-type doped material and transparent conduction applications are found to start only above 3.9 eV and are allowed for only one polarization, and several higher band transitions are forbidden by symmetry. Alternative crystal structures, such as $R\bar{3}m$ and a rocksalt type phase with tetragonally distorted $P4/mmm$ spacegroup, both with octahedral coordination of the cations are also investigated. They are found to have higher energy but about 20 \% smaller volume per formula unit. The transition pressures to these phases are determined and for LiGaO2 found to be in good agreement with experimental studies. The $R\bar{3}m$phase also has a comparably high but slightly indirect band gap while the rocksalt type phase if found to have a considerably smaller gap of about 3.1 eV in LiGaO2 and 1.0 eV in NaGaO2.

15 pages, 18 figures, 14 tables

References in corpus (14)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Quasiparticle self-consistent $GW$ method; a basis for the independent-particle approximation
• Fröhlich electron-phonon vertex from first principles
• Ab-initio Prediction of Conduction Band Spin Splitting in Zincblende Semiconductors
• Adequacy of Approximations in GW Theory
• Questaal: a package of electronic structure methods based on the linear muffin-tin orbital technique
• Predominance of non-adiabatic effects in zero-point renormalization of the electronic band gap
• Accurate energy bands calculated by the hybrid quasiparticle self-consistent GW method implemented in the ecalj package
• Accurate optical properties from first principles: a Quasiparticle Self consistent GW plus Bethe-Salpeter Equation approach
• All-electron quasi-particle self-consistent $GW$ band structures for SrTiO${}_3$ including lattice polarization corrections in different phase
• Influence of Fröhlich polaron coupling on renormalized electron bands in polar semiconductors. Results for zincblende GaN
• Lattice polarization effects on the screened Coulomb interaction $W$ of the GW approximation
• First-principles study of point defects in LiGaO2
• Computational Study of Electron Paramagnetic Resonance Spectra for Li and Ga Vacancies in LiGaO2

Cited by in corpus (6)

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• N${}_2$, NO and O${}_2$ molecules in LiGaO${}_2$ in both Ga and Li sites and their relation to the vacancies
• Computational study of defect complexes in $\beta$-LiGaO${}_2$ and their relation to the donor-acceptor-pair recombination
• Quasiparticle self-consistent $GW$ band structures and phase transitions of LiAlO${}_2$ in tetrahedrally and octahedrally coordinated structures
• First-principles study of the bandgap renormalization and optical property of $\beta$-LiGaO${}_2$