Vacancies in wurtzite GaN and AlN

Laaksonen, Kristina; Ganchenkova, Maria; Nieminen, Risto M.

doi:10.1088/0953-8984/21/1/015803

Cited by 88 publications

(70 citation statements)

References 19 publications

(39 reference statements)

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“…E F is the Fermi level, referenced to the valence-band maximum in the bulk and E V is the energy of the valence-band maximum (VBM) of the defect. If the formation energy is calculated in the infinite crystal, then VBM of the defect is equal to the VBM of the bulk (pristine) system [29]. The thermal transition energies ε(q/q') is defined as the Fermi energy where the lowestenergy charge state changes from q to q' as E F rises in the gap.…”

Section: Computational Detailsmentioning

confidence: 99%

Ab initio study of metastability of Eu3+ defect complexes in GaN

Ouma

Meyer

2014

Physica B: Condensed Matter

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Density functional theory (DFT) within the generalized gradient approximation (GGA) has been used to study the structural and electronic properties of Eu 3þ defect complexes in GaN under Ga-rich conditions. Two distinct configurations of the Eu Ga V N defect complex, the axial and basal configuration, have been investigated. We report two forms of metastable defects namely; the Negative U defect in the lower half of the GaN band-gap and a metastable defect with two distinct configurations each with levels at E C À0.46 eV and À0.56 eV in the upper half of the GaN band-gap.

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Section: Computational Detailsmentioning

confidence: 99%

Ab initio study of metastability of Eu3+ defect complexes in GaN

Ouma

Meyer

2014

Physica B: Condensed Matter

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“…However, when supercells of sufficiently large sizes are used, the interaction of the defect with the spurious periodic images and with the jellium background will become negligible. 32 Hence we used 192-atom supercells in most cases and, also, supercells with 256 atoms in some selected cases. Finite-size effects are taken into account in the formation energy calculations by considering the change in configuration energy (E conf = E def tot − E bulk tot ) and extrapolating to infinity.…”

Section: A Defect Formation Energymentioning

confidence: 99%

Energetics of intrinsic defects and their complexes in ZnO investigated by density functional calculations

et al. 2011

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Formation energies of various intrinsic defects and defect complexes in ZnO have been calculated using a density-functional-theory-based pseudopotential all-electron method. The various defects considered are oxygen vacancy ( Upon comparing the formation energies of these defects, we find that V O would be the dominant intrinsic defect under both Zn-rich and O-rich conditions and it is a deep double donor. Both Zn O and Zn i are found to be shallow donors. The low formation energy of donor-type intrinsic defects could lead to difficulty in achieving p-type conductivity in ZnO. Defect complexes have charge transitions deep inside the band gap. The red, yellow, and green photoluminescence peaks of undoped samples can be assigned to some of the defect complexes considered. It is believed that the red luminescence originates from an electronic transition in V O , but we find that it can originate from the antisite Zn O defect. Charge density and electron-localization function analyses have been used to understand the effect of these defects on the ZnO lattice. The electronic structure of ZnO with intrinsic defects has been studied using density-of-states and electronic band structure plots. The acceptor levels introduced by V Zn are relatively localized, making it difficult to achieve p-type conductivity with sufficient hole mobility.

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“…This is in reasonable agreement with our calculation. Third, the formation energies of isolated Al vacancies become very low as the Fermi-level approaches the conduction band [24][25][26]. This explains why the VL A band emerges only in n-type AlN, while it is absent in insulating material.…”

Section: àmentioning

confidence: 99%

“…Another possibility is oxygen, incorporating on nitrogen site, i.e. O N , whose concentration is typically in the order of 10 18 N ) at about 120 meV below the conduction band [26]. In contrast, Zhang et al [24], found that nitrogen vacancies only incorporate as deep donors, more than 1 eV below the conduction band, whereas Stampfl et al and Van de Walle [25] claimed that V N is forming a shallow donor in AlN.…”

Section: àmentioning

confidence: 99%

Ultraviolet luminescence in AlN

Schulz

Albrecht

Irmscher

et al. 2011

Physica Status Solidi (b)

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The defect related luminescence in the near UV region between 3 and 4 eV has been investigated in insulating, n-type and irradiation damaged AlN. A single luminescence band around 3.3 eV with a full width at half maximum of more than 500 meV, is attributed to a donor-acceptor pair transition at low temperatures. The substantial linewidth and a Stokes shift of around 1.3 eV result from strong electron-phonon coupling of the deep acceptor. While the chemical nature of the donor remains ambiguous, the acceptor species is attributed to the isolated Al vacancy, i.e. V 3ÀAl . This luminescence band might be interesting for studying n-type compensation mechanisms in AlN.

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Vacancies in wurtzite GaN and AlN

Cited by 88 publications

References 19 publications

Ab initio study of metastability of Eu3+ defect complexes in GaN

Ab initio study of metastability of Eu3+ defect complexes in GaN

Energetics of intrinsic defects and their complexes in ZnO investigated by density functional calculations

Ultraviolet luminescence in AlN

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