We investigate lattice ordering phenomena for the heterovalent ternaries that are based on the wurtzite lattice, under the constraint that the octet rule be preserved. We show that, with the single ...exception of a highly symmetric twinned structure, all allowed lattice orderings can be described by a pseudospin model corresponding to the two different stackings ABAB of rows of atoms in the basal plane that occur in the Pna2sub 1 and Pmc2sub 1 crystal structures. The Raman and photo-luminescence spectra of ZnSnNsub 2 are interpreted in light of the ordering model developed here. The observation that ZnSnNsub 2 orders in the Pna2sub 1 structure under appropriate growth conditions is consistent with the larger difference in the energies of formation of Pna2sub 1 the and Pmc2sub 1 structures for this material. The ordering model presented here has important implications for the optical, electronic, and lattice properties of all wurtzite-based heterovalent ternaries.
First-principles calculations are presented for Si, Ge, Sn doping of LiGaO2. Both Si Ga and Ge Ga are found to be shallow donors. Sn Ga is found to be a somewhat deeper donor. The site preference is ...studied and all three group-IV dopants are found to favor the Ga over the Li site when the Fermi level is in the upper part of the gap, corresponding to n-type doping and for Li-rich growth conditions. The prospects for n-type doping are thus favorable. N O is found to be amphoteric with both deep donor and acceptor type transition levels. Zn has a significant site competition between Zn Li (donor) and Zn Ga (acceptor) levels, which would pin the Fermi level in the middle of the gap. Thus, p-type doping cannot be achieved with these dopants.
Lu
(2022),
, 5529 uses incorrect explanations for their findings based on an incorrect application of ideas from tight-binding methods. An alternative qualitative explanation based on strain ...variations and a tight-binding model based on nearest neighbor interactions is provided.
Higher order topological tnsulators are d-spatial dimensional systems featuring topologically protected gapless states at their (d − n) -dimensional boundaries. With the help of ab initio ...calculations and tight-binding models along with symmetry considerations, we show that monolayer buckled honeycomb structures of group-V elements (Sb, As), which have already been synthesized, belong in this category and have a spinless charge fractionalization of e/2 at the corner states as well as weak topological edge states, protected by the S6 symmetry operation, which classify this system as a quadrupole topological insulator. The robustness of these edge and corner states to perturbations is explicitly demonstrated.
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