Lanthanide impurity level location in GaN, AlN, and ZnO

Dorenbos, P.; Kolk, Erik van der

doi:10.1117/12.698977

Cited by 23 publications

(19 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The trends on the splitting between the HO and LU 4f-related RE levels are in good agreement with that model [27]. As discussed in the previous paragraph for Gd in GaN, Gd in ZnO also has an U value that is considerably smaller than the respective HO-LU energy splitting, as shown in fig.…”

Section: (B)supporting

confidence: 75%

“…Our results showed otherwise, they indicated that all RE impurities in ZnO stay in a 3+ oxidation state, as for the RE impurities in GaN. Such results in ZnO are fully consistent with assumptions used in the phenomenological model [27]. For a RE in ZnO to achieve such oxidation state, it donates two electrons to stabilize the binding with the oxygen neighboring atoms, while the third electron populates the bottom of the ZnO conduction band.…”

supporting

confidence: 76%

“…As a result, the electronic structure of those systems cannot be described appropriately without the Hubbard correction. Therefore, a smaller U 4f value for Gd, as compared to other RE impurities, is enough to provide a proper description of the respective electronic structure.Consistent with the discussion for impurities in GaN, the trends along the RE series in ZnO are in excellent agreement with the phenomenological model [27], as shown in fig. 1(b).…”

supporting

confidence: 75%

“…Consistent with the discussion for impurities in GaN, the trends along the RE series in ZnO are in excellent agreement with the phenomenological model [27], as shown in fig. 1(b).…”

supporting

confidence: 75%

See 3 more Smart Citations

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Caroena

Machado

Justo

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

The electronic properties of lanthanide (from Eu to Tm) impurities in wurtzite gallium nitride and zinc oxide were investigated by first principles calculations, using an all electron methodology plus a Hubbard potential correction. The results indicated that the 4f-related energy levels remain outside the bandgap in both materials, in good agreement with a recent phenomenological model, based on experimental data. Additionally, zinc oxide doped with lanthanide impurities became an n-type material, showing a coupling between the 4f-related spin polarized states and the carriers.This coupling may generate spin polarized currents, which could lead to applications in spintronic devices. [2,3] devices. Rare earth lanthanide atoms exhibit partially filled 4f shells, and intra-4f electric dipole transitions are forbidden for the free ions. On the other hand, the respective transition probabilities increase considerably when the ions are placed in a crystal field, that splits the 4f-related energy levels, modifying the dipole selection rules and leading to luminescent centers [4].Although theoretical modeling has been used to investigate the properties of RE-related materials [5,6], several methodological challenges have hindered an appropriate description of the 4f-related states in crystalline environments, such as RE impurities in semiconductors.It is well documented that the density functional theory generally fails in describing highly correlated systems, such as the interactions in 4f-related electronic states. Such limitations could in part be overcome with the introduction of an on-site Hubbard U potential correction [7][8][9]. One of the major outcomes of this correction is a better description of the energy splitting between occupied and unoccupied 4f-related electronic levels. We have recently shown that this procedure provides a good description of the electronic structure of metallic RE crystals [10], when compared to available experimental data [11]. Here, we show that the same procedure is also appropriate to describe the trends on the 4f-related energy levels of RE impurities (from Eu to Tm), with respect to the bandgap, in wurtzite gallium nitride and zinc oxide crystals. The results were discussed in the context of a recent phenomenological model to determine the energy positions of 4f-related electronic systems in crystalline environments [12]. Our results also indicate that doping ZnO with lanthanide impurities leads to a ntype material, with a magnetic coupling between the 4f-related states and the carriers.This suggests that such systems could generate spin polarized carrier currents, allowing to envision potential applications in spintronic devices.In RE lanthanide atoms, the 4f states play a minor role on bonding, staying in an atomiclike configuration. Therefore, those atoms bind to their neighboring ones through their outer (5d, 6s, and 6p) atomic valence states [11]. Earlier theoretical investigations generally considered the 4f electrons as core states, with constrained occupations ...

show abstract

Section: (B)supporting

confidence: 75%

supporting

confidence: 76%

supporting

confidence: 75%

“…Consistent with the discussion for impurities in GaN, the trends along the RE series in ZnO are in excellent agreement with the phenomenological model [27], as shown in fig. 1(b).…”

supporting

confidence: 75%

See 2 more Smart Citations

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Caroena

Machado

Justo

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…The error is assumed to be systematic for each lanthanide and on the order of 0.5 eV [58]. It needs to be mentioned here that a similar lanthanide energy level scheme for a compound with comparable band gap, namely GaN (band gap 3.42 eV), was published [55,59]. Dorenbos had already published numerous papers connected to such energy diagrams for various compounds, for example YPO 4 [54], Y 2 O 3 , CaBPO 5 , KCl [60], CaF 2 [54], Al x Ga 1 - x N [55] and therefore following his procedure was also considered applicable for our KLuS 2 ternary sulfide.…”

Section: Resultsmentioning

confidence: 99%

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

et al. 2015

View full text Add to dashboard Cite

Eu-doped ternary sulfides of general formula ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y) are presented as a novel interesting material family which may find usage as X-ray phosphors or solid state white light emitting diode (LED) lighting. Samples were synthesized in the form of transparent crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. Their physical properties were investigated by means of X-ray diffraction, time-resolved photoluminescence spectroscopy, electron paramagnetic resonance, and X-ray excited fluorescence. Corresponding characteristics, including absorption, radioluminescence, photoluminescence excitation and emission spectra, and decay kinetics curves, were measured and evaluated in a broad temperature range (8–800 K). Calculations including quantum local crystal field potential and spin-Hamiltonian for a paramagnetic particle in D3d local symmetry and phenomenological model dealing with excited state dynamics were performed to explain the experimentally observed features. Based on the results, an energy diagram of lanthanide energy levels in KLuS2 is proposed. Color model xy-coordinates are used to compare effects of dopants on the resulting spectrum. The application potential of the mentioned compounds in the field of white LED solid state lighting or X-ray phosphors is thoroughly discussed.

show abstract

Nanosheet‐Based Microspheres of Eu³⁺‐doped ZnO with Efficient Energy Transfer from ZnO to Eu³⁺ at Room Temperature

et al. 2007

View full text Add to dashboard Cite

Rare earth (RE 3+ )-doped semiconductors, such as GaN:RE [1] and Si:Er, [2] are technologically important materials in optoelectric devices and have received considerable interest. In most of these applications, efficient energy transfer from host to the RE 3+ is desired. ZnO with a bandgap of 3.37 eV and a bound exciton energy of 60 meV is also an important semiconductor for which UV, [3] blue, [4] and green [5] emissions are widely reported, but intense red emissions are still lacking. (Fig. 1a) at the bottom of the autoclave, which is decomposed into wurtzite ZnO after further annealing at 400°C (Fig. 1b). It is worth noting that the saturated concentration of Eu 3+ in ZnO is relatively low, smaller than 1.0 % (ca. 4.2 × 10 26 cm -3 ). As shown in Fig. 1b Fig. 1s). In addition, no meaningful shift in the X-ray diffraction (XRD) peaks for ZnO were detected, which indicates a low concentration of Eu 3+ in ZnO.Nevertheless, the X-ray photoelectron spectroscopy (XPS) 3d spectrum for Eu provides convincing evidence for Eu 3+ doping in ZnO (see Supporting Information, Fig. 2s). Consequently, in samples for optical measurements, the starting concentration of Eu 3+ was lower than 1.0 % to exclude the disturbance from the Eu 3+ ions outside of ZnO.Hosono et al. [12] proposed that LHZC follows a sheetlike growth feature along the hydrophilic b-and c-axes, whereas the (100) surface is hydrophobic. We describe the mechanism for the nucleation and crystal growth of LHZC microspheres as follows: after homogenous nucleation in solution, nuclea- COMMUNICATION 4510

show abstract

Lanthanide impurity level location in GaN, AlN, and ZnO

Cited by 23 publications

References 29 publications

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

Nanosheet‐Based Microspheres of Eu³⁺‐doped ZnO with Efficient Energy Transfer from ZnO to Eu³⁺ at Room Temperature

Contact Info

Product

Resources

About

Lanthanide impurity level location in GaN, AlN, and ZnO

Cited by 23 publications

References 29 publications

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

Nanosheet‐Based Microspheres of Eu3+‐doped ZnO with Efficient Energy Transfer from ZnO to Eu3+ at Room Temperature

Contact Info

Product

Resources

About

Nanosheet‐Based Microspheres of Eu³⁺‐doped ZnO with Efficient Energy Transfer from ZnO to Eu³⁺ at Room Temperature