Location of lanthanide impurity levels in the III-V semiconductor GaN

Dorenbos, P.; Kolk, Erik van der

doi:10.1063/1.2336716

Cited by 82 publications

(74 citation statements)

References 27 publications

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“…For GaN, shown in fig. 1(a), our results give trends along the RE series in excellent agreement with those of a phenomenological model based on experimental data [24,25]. However, our 3 calculations provide absolute values for the HO levels which are about 2 eV lower when compared to that model.…”

supporting

confidence: 76%

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

Caroena

Machado

Justo

et al. 2013

Applied Physics Letters

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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 ...

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supporting

confidence: 76%

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

Caroena

Machado

Justo

et al. 2013

Applied Physics Letters

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“…It increases from 0.008 eV for pure GaN to 0.15 eV for x=0. 15, and the value for T 0.5 where the luminescence intensity drops by 50% increases from 27 K to 186 K. The data points in [10] for x=0.36 appears to disagree with expectation. Fig.…”

Section: Ganmentioning

confidence: 50%

“…We are aware that at this stage the assumption on the value for ∆E(Eu) and the assignment of the 355 nm band to the CT of Eu 3+ may seem tentative. However, based on the electronegativity of the nitride anion we do expect the energy of the CT band to Eu 3+ around 3.0 to 3.5 eV [15,16,13]. We also expect that the energy of the CT band to Eu 3+ on the Al site in AlN is at higher energy than when on the Ga site in GaN.…”

Section: Ganmentioning

confidence: 99%

“…First the historic developments leading to the method of level positioning is briefly presented. Then it is applied to place the level energies of the divalent and trivalent lanthanide ions in GaN [15] and AlN. Next we demonstrate how the luminescence properties of Tb 3+ emission changes with the alloying parameter x in Al x Ga 1-x N, and finally a tentative scheme for ZnO is presented.…”

Section: Introductionmentioning

confidence: 99%

“…Recently methods became available that predict level locations for all the lanthanides in inorganic compounds [12,13,14]. Recently we applied those methods for the first time to GaN, AlN, and their alloys Al x Ga 1-x N and proposed level schemes with the location of the ground states of all divalent and all trivalent lanthanides [15,16] Because this method is still relatively new and not yet adopted in the field of lanthanide doped III-V and II-VI semiconductor research, we will review the method in this work and illustrate how the schemes for GaN and AlN and their alloys were made. Also the main difference with schemes in wide band gap inorganic compounds like YPO 4 is illustrated.…”

Section: Introductionmentioning

confidence: 99%

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Lanthanide impurity level location in GaN, AlN, and ZnO

Dorenbos

Kolk

2007

SPIE Proceedings

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A method that has proven succesful in locating the energy levels of divalent and trivalent lanthanide ions (Ce, Pr,..., Eu,...Yb, Lu) in wide band gap inorganic compounds like YPO 4 and CaF 2 is applied to locate lanthanide levels in the wideband semiconductors GaN, AlN, their solid solutions Al x Ga 1-x N, and ZnO. The proposed schemes provide a description of relevant optical and luminescence properties of these lanthanide doped semiconductors. Especially, the relation between thermal quenching of Tb 3+ emission and the location of the energy levels is explained.

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

et al. 2007

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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

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Location of lanthanide impurity levels in the III-V semiconductor GaN

Cited by 82 publications

References 27 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

Lanthanide impurity level location in GaN, AlN, and ZnO

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

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Location of lanthanide impurity levels in the III-V semiconductor GaN

Cited by 82 publications

References 27 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

Lanthanide impurity level location in GaN, AlN, and ZnO

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

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Product

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