Branch-point energies and band discontinuities of III-nitrides and III-/II-oxides from quasiparticle band-structure calculations

Abstract

Using quasiparticle band structures based on modern electronic-structure theory, we calculate the branch-point energies for zinc blende ͑GaN, InN͒, rocksalt ͑MgO, CdO͒, wurtzite ͑AlN, GaN, InN, ZnO͒, and rhombohedral crystals ͑In 2 O 3 ͒. For InN, CdO, ZnO, and also In 2 O 3 the branch-point energies are located within the lowest conduction band. These predictions are in agreement with observations of surface electron accumulation ͑InN, CdO͒ or conducting behavior of the oxides ͑ZnO, In 2 O 3 ͒. The results are used to predict natural band offsets for the materials investigated.

Native point defects in CuIn1−xGaxSe2: hybrid density functional calculations predict the origin of p- and n-type conductivity

“…Guidelines for this choice have been established in Ref. 20, which for the CIGS compounds with 64 electrons (in the 1 × 1 × 2 supercell, not counting the d-electrons), lead to averaging over 16 valence bands and 8 conduction bands.…”

“…The main advantage of the alignment via slabs is that it contains an absolute reference: the potential in vacuum, hence also giving the electron affinities. The other method, using the concept of the branch-point energy (E BP ), was proposed by A. Schleife et al 20 and solely relies on the band structures of the bulk materials. The E BP is calculated as an average of the electronic eigenvalues over the Brillouin zone, defined in Ref.…”

“…The E BP is calculated as an average of the electronic eigenvalues over the Brillouin zone, defined in Ref. 20.…”

Conductivity in transparent oxide semiconductors

“…12 [170], but can also be seen in calculations of the electronic structure of the other TCOs [68,[171][172][173][174]. Such a band structure means that the Brillouin-zone-averaged band gap, and consequently also the CNL [175], are situated above the low-lying CBM, rather than within the fundamental band gap [63,167]. We also note that the highly dispersive conduction band, and so relatively small effective mass, is crucial in obtaining sufficiently high mobilities in these materials to ensure adequate conductivity.…”

“…Indeed, from direct measurements, measurements of valence band offsets (allowing band alignment relative to the CNL), and theoretical calculations [63,135,[163][164][165][166][167], the CNL has been found to occur above the CBM across the TCOs, as summarized in Fig. 11.…”