Choosing the correct hybrid for defect calculations: A case study on intrinsic carrier trapping in 
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Deák, Péter; Hồ, Quốc Duy; Seemann, F. W.; Aradi, Bálint; Lorke, Michael; Frauenheim, Thomas

doi:10.1103/physrevb.95.075208

Cited by 206 publications

(181 citation statements)

References 92 publications

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“…To date, there have been some theoretical calculations that predict states near these energy values based on the various oxygen and gallium vacancy related defects of several charge states and configurations but more work must be carried out in conjunction with careful experiments to elucidate further. 16,42,[45][46][47] The remaining states at E C À 1.27 eV (detected in trace amounts by DLOS), and the set of levels at E C À 0.18 eV À 0.21 eV found by DLTS, were not seen in the earlier EFG studied material. The role of vastly different growth methods, or the use of a different dopant could be responsible for these differences, and this would not be surprising.…”

Section: Model/parametermentioning

confidence: 94%

“…While this level could possibly be related to the vacancies given its position in the bandgap based on predictions by theoretical calculations, 42,43 it also aligns quite well with a previous DLOS signature seen on EFG material that has been suggested to possibly be related to self-trapped holes (STH). 11,44,45 Regardless, the very similar DLOS spectrum and concentration for this level detected in b-Ga 2 O 3 materials synthesized by very different methods implies a common source that appears to be less dependent on the large differences in growth methods, and more work is needed to fully understand the STH presence in DLOS measurements. Two other states also bear similarities, E C À 2.00 eV (compared with E C À 2.16 eV for EFG), detected by DLOS, and E C À 0.98 eV (compared with E C À 1.0 eV for EFG), detected by DLTS.…”

Section: Model/parametermentioning

confidence: 99%

“…Theoretical calculations have predicted the presence of vacancy-related energy levels near E C À 0.8 eV, though there is some controversy regarding the specific vacancy type (oxygen or gallium) in those works. 16,45,46 If indeed this is a vacancy-related state, it would not be surprising given that the different thermodynamic conditions of PAMBE vs. melt-based bulk crystal growth would generate different types and concentrations of Ga and O vacancies. However, a recent study has theoretically predicted that Fe Ga substitutional impurities can also manifest as a state near E C À 0.8 eV, and indeed an experimental correlation between the Fe concentration and the concentration of this trap within bulk substrate materials was observed along with an insensitivity to high energy particle irradiation that corroborates an extrinsic source.…”

Section: Model/parametermentioning

confidence: 99%

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Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy

Farzana

Ahmadi

Speck

et al. 2018

Journal of Applied Physics

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Deep level defects were characterized in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy (PAMBE) using deep level optical spectroscopy (DLOS) and deep level transient (thermal) spectroscopy (DLTS) applied to Ni/β-Ga2O3:Ge (010) Schottky diodes that displayed Schottky barrier heights of 1.50 eV. DLOS revealed states at EC − 2.00 eV, EC − 3.25 eV, and EC − 4.37 eV with concentrations on the order of 1016 cm−3, and a lower concentration level at EC − 1.27 eV. In contrast to these states within the middle and lower parts of the bandgap probed by DLOS, DLTS measurements revealed much lower concentrations of states within the upper bandgap region at EC − 0.1 – 0.2 eV and EC − 0.98 eV. There was no evidence of the commonly observed trap state at ∼EC − 0.82 eV that has been reported to dominate the DLTS spectrum in substrate materials synthesized by melt-based growth methods such as edge defined film fed growth (EFG) and Czochralski methods [Zhang et al., Appl. Phys. Lett. 108, 052105 (2016) and Irmscher et al., J. Appl. Phys. 110, 063720 (2011)]. This strong sensitivity of defect incorporation on crystal growth method and conditions is unsurprising, which for PAMBE-grown β-Ga2O3:Ge manifests as a relatively “clean” upper part of the bandgap. However, the states at ∼EC − 0.98 eV, EC − 2.00 eV, and EC − 4.37 eV are reminiscent of similar findings from these earlier results on EFG-grown materials, suggesting that possible common sources might also be present irrespective of growth method.

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Section: Model/parametermentioning

confidence: 94%

Section: Model/parametermentioning

confidence: 99%

Section: Model/parametermentioning

confidence: 99%

See 1 more Smart Citation

Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy

Farzana

Ahmadi

Speck

et al. 2018

Journal of Applied Physics

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“…The primary purpose of our DFT calculations is to identify band-to-band transitions and to calculate parameters of CP transitions, and compare these with contributions to the experimental dielectric function of β-Ga 2 O 3 . We note that for our purpose the band structure calculations at the hybrid Hartree-Fock-DFT (HF-DFT) level are sufficient [35,36].…”

Section: Introductionmentioning

confidence: 99%

Band-to-band transitions, selection rules, effective mass, and excitonic contributions in monoclinic β−Ga2O3

et al. 2017

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We employ an eigenpolarization model including the description of direction dependent excitonic effects for rendering critical point structures within the dielectric function tensor of monoclinic β-Ga 2 O 3 yielding a comprehensive analysis of generalized ellipsometry data obtained from 0.75-9 eV. The eigenpolarization model permits complete description of the dielectric response. We obtain, for single-electron and excitonic band-to-band transitions, anisotropic critical point model parameters including their polarization vectors within the monoclinic lattice. We compare our experimental analysis with results from density functional theory calculations performed using the Gaussian-attenuation-Perdew-Burke-Ernzerhof hybrid density functional. We present and discuss the order of the fundamental direct band-to-band transitions and their polarization selection rules, the electron and hole effective mass parameters for the three lowest band-to-band transitions, and their excitonic contributions. We find that the effective masses for holes are highly anisotropic and correlate with the selection rules for the fundamental band-to-band transitions. The observed transitions are polarized close to the direction of the lowest hole effective mass for the valence band participating in the transition.

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“…7 In theoretical studies, the basic features of the electronic structure of both the a-and b-phases of Ga 2 O 3 like band structure, partial and joint density of states (DOS) are reported, 7 and a strong covalent bonding is concluded. 7,8 All theoretical studies 5,[7][8][9] agree on the partial density of states (pDOS) for the valence states is of the O2p and Ga4sp character.…”

Section: Introductionmentioning

confidence: 93%

Intrinsic electronic defects and multiple-atom processes in the oxidic semiconductor Ga2O3

Schmeißer

Henkel

2018

Journal of Applied Physics

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We report on the electronic structure of gallium oxide (Ga2O3) single crystals as studied by resonant photoelectron spectroscopy (resPES). We identify intrinsic electronic defects that are formed by mixed-atomic valence states. We differentiate three coexisting defect states that differ in their electronic correlation energy and their spatial localization lengths. Their relative abundance is described by a fractional ionicity with covalent and ionic bonding contributions. For Ga2O3, our analyses of the resPES data enable us to derive two main aspects: first, experimental access is given to determine the ionicity based on the original concepts of Pauling and Phillips. Second, we report on multi-atomic energy loss processes in the Ga2p core level and X-ray absorption data. The two experimental findings can be explained consistently in the same context of mixed-atomic valence states and intrinsic electronic defects.

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Choosing the correct hybrid for defect calculations: A case study on intrinsic carrier trapping in β−Ga2O3

Cited by 206 publications

References 92 publications

Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy

Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy

Band-to-band transitions, selection rules, effective mass, and excitonic contributions in monoclinic β−Ga2O3

Intrinsic electronic defects and multiple-atom processes in the oxidic semiconductor Ga2O3

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