Stability and electronic properties of GaN phases with inversion symmetry to inherently inhibit polarization

Strain Engineering to Release Trapped Hole Carriers in p-Type Haeckelite GaN

“…The atomic structures of pristine w -GaN and 4|8-GaN were optimized with the GGA-PBE functional, and the band structures are calculated with both GGA-PBE and HSE functionals. w -GaN exhibits a strong piezoelectric effect along the c axis together with strong polarity of the [0001̅] surface, while 4|8-GaN has rigorous zero polarization in the z axis, which significantly stabilizes the 4|8-GaN phase compared to w -GaN for few-atom-thick films, i.e., for films of from 2 to 18 monolayers, 4|8-GaN is the most stable phase. ,, The band gap of w -GaN obtained with the HSE functional is in good agreement with the experimental value (3.4 eV), while PBE-GGA gravely underestimates the band gap. The HSE functional predicts a direct band gap of 3.36 eV at the Γ point for 4|8-GaN, which ensures a high hole–electron recombination rate of 4|8-GaN similar to w -GaN. , Apart from the band gap underestimation by GGA-PBE for w -GaN and 4|8-GaN, their band dispersion properties are very similar to those obtained by the HSE functional.…”

Peculiar bond characters of fivefold coordinated octet compound crystals

“…[27][28][29] Exhibiting differing physical properties, 6 polymorphs of a compound are desired for different applications. [30][31][32] While fourfold coordinated zinc blende and wurtzite phases as well as numerous stacking variations are used in current technologies, the search for novel polymorphs is a lasting endeavor. 14,32,33 Compared with the wurtzite phase, the vefold coordinated structure possesses higher symmetry that results in technologically favorable physical properties (e.g., absence of spontaneous polarization) for certain applications.…”

Electronic Structures of Group III–V Element Haeckelite Compounds: A Novel Family of Semiconductors, Dirac Semimetals, and Topological Insulators

“…For example, it was predicted that the haeckelite bulk of C [44] and GaN could be semiconducting. [45,46] Experimentally, only the haeckelite crystal of β-BeO has been synthesized, [47] which is a semiconducting compound. Fascinated by interesting electronic properties of 2D T-lattice structures and to fill the gap in scientific knowledge on haeckelite crystal, here, by performing a set of first-principles calculations we have studied the electronic structures of twenty haeckelite XY compounds (X = B, Al, Ga, In, Tl; Y = N, P, As, Sb) belonging to the bigger family of III-V element compounds.…”