Vacancy-type defects in Er-doped GaN studied by a monoenergetic positron beam

Uedono, Akira; Shaoqiang, C.; Jongwon, S.; Ito, Kyoji; Nakamori, H.; Honda, Naoto; Tomita, S.; Akimoto, Katsuhiro; Kawamura, Hiroshi; Ishibashi, Shoji

doi:10.1063/1.2932166

Cited by 24 publications

(23 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Er-doped GaN samples were grown on sapphire substrates by gas-source molecular beam epitaxy [16,17]. Metallic Ga and Er were evaporated from conventional Knudsen effusion cells.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Point defects in group-III nitride semiconductors studied by positron annihilation

Uedono

Ishibashi

Ohdaira

et al. 2009

Journal of Crystal Growth

Self Cite

View full text Add to dashboard Cite

“…Er-doped GaN samples were grown on sapphire substrates by gas-source molecular beam epitaxy [16,17]. Metallic Ga and Er were evaporated from conventional Knudsen effusion cells.…”

Section: Methodsmentioning

confidence: 99%

“…Fig. 4 shows the relationship between the S values in Er-doped GaN and the Er concentration [Er] [17]. The variation of the integrated intensity of the 511 nm PL line is also shown.…”

Section: Vacancy-type Defects In Ion-implanted Ganmentioning

confidence: 98%

Point defects in group-III nitride semiconductors studied by positron annihilation

Uedono

Ishibashi

Ohdaira

et al. 2009

Journal of Crystal Growth

Self Cite

View full text Add to dashboard Cite

“…As an ion, Eu can exist in two oxidation states: Eu 2 þ and Eu 3 þ , with the former being rarely encountered in semiconductors. Several studies have been done on Eu in GaN both theoretically [2][3][4]9,10] and experimentally [11][12][13][14][15][16][17][18]. However, to the best of our knowledge, it is only Auret et al [16] who recently experimentally observed a metastable defect with charge-state controlled metastability in 300 keV Eu doped GaN, annealed at 1000 1C.…”

Section: Introductionmentioning

confidence: 98%

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

Ouma

Meyer

2014

Physica B: Condensed Matter

View full text Add to dashboard Cite

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.

show abstract

“…In addition, doping procedures of magnetic impurities have been reported to introduce cation vacancies and their complexes. 15) At this stage, it is imperative to examine yet-to-be-discovered intrinsic spin-related properties of defects in nitride semiconductors.…”

mentioning

confidence: 99%

Stabilization Mechanism of Vacancies in Group-III Nitrides: Exchange Splitting and Electron Transfer

Gohda

Oshiyama

2010

J. Phys. Soc. Jpn.

View full text Add to dashboard Cite

We report first-principles calculations on mono-, di-, and tri-vacancies in group-III nitrides with clarifying two distinctive mechanisms in stabilization of the vacancy: Spin polarization due to exchange splitting of nitrogen-dangling bond states and electron transfer caused by breathing relaxation of cations. We also find that the significance of the two mechanisms strongly depends on the charge state of the vacancy and thus the Fermi-level position in the gap at which the charge state changes (the thermodynamic charge-state level) cannot be determined from single-electron levels at a certain charge state. Group IV elements such as Si and Ge are semiconductors in their condensed phases where the sp 3 hybridization forms a network of chemical bonds with the diamond structure. Pairs of group III and V elements are condensed to be compound semiconductors in an essentially identical manner. Defects such as the atomic vacancy strongly affect properties of host semiconductors by inducing deep levels in the energy gap. The deep level is generally localized in space, so that electron-electron interaction such as exchange interaction could be important. Yet experimental and theoretical efforts in the past [1][2][3] have clarified that covalency in those materials is significant determining material properties and rebonding of neighboring orbitals with symmetry lowering Jahn-Teller effect is a principal characteristic of the atomic vacancy.Group-III nitride semiconductors are unique in the sense that the cation is much larger than the anion: Atomic radii of Al, Ga, and In are 1.43, 1.41, and 1.66 Å , respectively, whereas the radius of N is 0.75 Å . Then if a cation atom is removed, the remaining N dangling bonds hardly rebond with each other, which causes the spin polarization around vacancies, and unprecedented properties are expected. Due to direct energy gaps corresponding to a range from infrared to ultraviolet wavelengths, group-III nitrides are important in optoelectronics.4) For microscopic identification of point defects, extensive calculations from first principles have been performed for GaN. 5,6) However, the possibility of the spin polarization of the cation vacancy explained above has been overlooked in those calculations. Although ferromagnetic behaviors in GaN doped with magnetic impurities have been reported [7][8][9][10] and a role of the cation monovacancy is examined in recent calculations, [11][12][13][14] it is certainly fair to say that our knowledge on defect spins is quite limited. In addition, doping procedures of magnetic impurities have been reported to introduce cation vacancies and their complexes.15) At this stage, it is imperative to examine yet-to-be-discovered intrinsic spin-related properties of defects in nitride semiconductors.Here, we report first-principles calculations that clarify the spin polarization and the lattice relaxation of mono-and multi-vacancies (V n ) with various charge states in group-III nitrides. We demonstrate that nontrivial dependence of spin configurations on ...

show abstract

Vacancy-type defects in Er-doped GaN studied by a monoenergetic positron beam

Cited by 24 publications

References 31 publications

Point defects in group-III nitride semiconductors studied by positron annihilation

Point defects in group-III nitride semiconductors studied by positron annihilation

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

Stabilization Mechanism of Vacancies in Group-III Nitrides: Exchange Splitting and Electron Transfer

Contact Info

Product

Resources

About