Broad luminescence from donor-complexed 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Li</mml:mi><mml:mtext>Zn</mml:mtext></mml:msub></mml:math>
 and 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Na</mml:mi><mml:mtext>Zn</mml:mtext></mml:msub></mml:math>
 acceptors in ZnO

Frodason, Ymir Kalmann; Johansen, K. M.; Galeckas, Augustinas; Vines, Lasse

doi:10.1103/physrevb.100.184102

Cited by 11 publications

(5 citation statements)

References 93 publications

(198 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, Na and K reside close to the ideal Zn site for both charge states [7]. This result is similar to what has been found for these impurities in ZnO [30].…”

Section: A LI Configurations and Migration In Znsnnsupporting

confidence: 88%

Li and group-III impurity doping in ZnSnN2 : Potential and limitations

Olsen

Frodason

Hommedal

et al. 2022

Phys. Rev. Materials

View full text Add to dashboard Cite

II-IV nitrides and their alloys represent an earth-abundant and potentially cost-efficient alternative to the well-developed AlN-GaN-InN system. A major drawback with the II-IV nitrides is that ZnSnN 2 , the lowest band gap material, exhibits unfavorably high carrier concentrations for as-grown, stoichiometric material, limiting the material systems potential use in applications such as solar cells and light-emitting diodes. Lithium (Li) has been suggested as a shallow acceptor defect in ZnSnN 2 if substituting for Zn, and hence doping with Li has been identified as a possible way to improve the electronic properties. Herein, theoretical calculations by hybrid functional density functional theory have been employed and extended to include defect complexes as well, which to this point remained unexplored. The calculations reveal that even though Li on the Zn site (the Li Zn ) is an acceptor, the defect may easily complex with the Li i donor, rendering the complex neutral. Our theoretical findings are supported by a Li-doping series of ZnSnN 2 , where a doping concentration ranging from 2.10 × 10 19 cm −3 to 1.85 × 10 20 cm −3 was obtained. The n-type carrier concentration was found to be unaffected by the doping concentration, and no systematic change in the absorption onset, probably affected by a Burstein-Moss shift, was observed. Possible group-III dopants, as have been found to yield interesting results for ZnGeN 2 , such as In, Ga, Al, and B, have also been investigated as an alternative dopant in ZnSnN 2 .

show abstract

“…In contrast, Na and K reside close to the ideal Zn site for both charge states [7]. This result is similar to what has been found for these impurities in ZnO [30].…”

Section: A LI Configurations and Migration In Znsnnsupporting

confidence: 88%

Li and group-III impurity doping in ZnSnN2 : Potential and limitations

Olsen

Frodason

Hommedal

et al. 2022

Phys. Rev. Materials

View full text Add to dashboard Cite

show abstract

“…The strong polaronic distortion (∆Q ≈ 1.3-1.6 u 1/2 A) results in large relaxation energies (Franck-Condon shifts) in the 0.6-1 eV range (depending on the defect). Such strong electron-phonon coupling can be expected to result in significant vibrational broadening of the absorption onsets, in line with experimental data 7,42 . In this case, the calculated absorption energies of the order of 1.48 eV and 1.5-1.8 eV for Li Ni and V Ni , respectively, reproduces the experimental observations well.…”

Section: E Hybrid-functional Calculationssupporting

confidence: 85%

Light absorption and emission by defects in doped nickel oxide

Karsthof¹,

Frodason²,

Galeckas³

et al. 2022

Preprint

View full text Add to dashboard Cite

Nickel oxide is a versatile p-type semiconducting oxide with many applications in opto-electronic devices, but high doping concentrations are often required to achieve necessary electrical conductivity. In contrast to many other transparent oxide semiconductors, even moderate levels of doping of NiO can lead to significant optical absorption in the visible spectral range, limiting the application range of the material. This correlation has been reported extensively in literature, but its origin has been unknown until now. This work combines experimental data on optical properties from a variety of NiO samples with results from hybrid density functional theory calculations. It shows that strong electron-phonon interaction leads to a significant blue shift (0.6-1 eV) of electronic transitions from the valence band maximum to defect states by light absorption with respect to the thermodynamic charge transition levels. This essentially renders NiO a narrow-gap semiconductor by defect band formation already at moderate doping levels, with strong light absorption for photon energies of approximately 1 eV. The calculations are also shown to be fully consistent with experimental data on defect-related light emission in NiO.

show abstract

“…The intensity of this band increases slightly with Na + content in ZnO. As it has been reported previously, Na + ion can occupy a Zn site to form the acceptor complexe NaZn whose energy level is located near the valence band [39]. Thus, the formed acceptor complex contributes to the blue-green emission from ZnO nanocrystals.…”

Section: Luminescence Studysupporting

confidence: 60%

Improvement of Luminescence and Photocatalytic Performance of ZnO:Eu3+ Nanocrystals Activated by Na+ Ions

et al. 2023

View full text Add to dashboard Cite

Undoped and codoped (Eu/Na) ZnO nanocrystals (NCs) were successfully manufactured through an economical sol-gel method. X-ray diffraction (XRD) analysis demonstrated pure hexagonal wurtzite structure without secondary phases for all the samples. The size of the NCs was found to decrease with codoping by Eu3+/Na+ which is related to the existence of strain and stress in the lattice. The dominance of the E2(high) mode in Raman spectra indicates the good crystallinity of the samples. The study from the X-ray photoelectron spectroscopy (XPS) shows the successful insertion of both Eu3+ and Na+ ions into the ZnO lattice and the generation of the zinc and oxygen vacancies (Vo) defects. The band gap energy was reduced and the Urbach energy increased with Na+ content, proving the distortion of the lattice. From the photoluminescence (PL) study, the activation of the Eu3+ ions by Na+ ones was evidenced. Longer PL lifetimes were obtained from Eu3+ ions when they were sensitized by Na+, which may be beneficial to several applications. A process of excitation transfer from both the ZnO host and Na+ sensitizers to the Eu3+ ions was evidenced and discussed. As an application, we tested the performances of the prepared NCs as photocatalysts for Rhodamine B photodegradation under sunlight irradiation. The ZnO NCs codoped with 1% Eu/4% Na displayed the best photodegradation rate with a good stability and a high kinetic rate constant k of 0.021 min−1. The photocatalytic mechanism is discussed in terms of longer radiative recombination from Eu3+ and the generated oxygen vacancies.

show abstract

Broad luminescence from donor-complexed LiZn and NaZn acceptors in ZnO

Cited by 11 publications

References 93 publications

Li and group-III impurity doping in ZnSnN2 : Potential and limitations

Li and group-III impurity doping in ZnSnN2 : Potential and limitations

Light absorption and emission by defects in doped nickel oxide

Improvement of Luminescence and Photocatalytic Performance of ZnO:Eu3+ Nanocrystals Activated by Na+ Ions

Contact Info

Product

Resources

About