The influence of defect drift in external electric field on green luminescence of ZnO single crystals

Korsunska, N.; Borkovska, L.; Bulakh, B. M.; Khomenkova, L.; Кушниренко, В. И.; Маркевич, И. В.

doi:10.1016/s0022-2313(02)00634-8

Cited by 137 publications

(82 citation statements)

References 15 publications

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“…The origin of this band has been suggested to be related to oxygen vacancies (V O ) or zinc vacancies (V Zn ). [31][32][33] Other studies found that this green band in ZnO can be attributed also to complex defects such as zinc interstitial (Zn i ) 34 or O Zn antisites. 35 Moreover, deep-level transient spectroscopy (DLTS), 36,37 electron paramagnetic resonance, 38,39 and optically detected magnetic resonance, 37,39,40 have confirmed that this band is related to electron transition from V O , as a deep donor level to recombine with a hole in the valence band.…”

Section: Resultsmentioning

confidence: 99%

Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

Flemban

Sequeira

Zhang

et al. 2016

Journal of Applied Physics

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Gd-doped ZnO thin films were prepared using pulsed laser deposition at different oxygen pressures and varied Gd concentrations. The effects of oxygen deficiency-related defects on the Gd incorporation, optical and structural properties, were explored by studying the impact of oxygen pressure during deposition and post-growth thermal annealing in vacuum. Rutherford Backscattering Spectrometry revealed that the Gd concentration increases with increasing oxygen pressure for samples grown with the same Gd-doped ZnO target. Unexpectedly, the c-lattice parameter of the samples tends to decrease with increasing Gd concentration, suggesting that Gd-defect complexes play an important role in the structural properties. Using low-temperature photoluminescence (PL), Raman measurements and density functional theory calculations, we identified oxygen vacancies as the dominant intrinsic point defects. PL spectra show a defect band related to oxygen vacancies for samples grown at oxygen deficiency. V C 2016 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 99%

Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films

Flemban

Sequeira

Zhang

et al. 2016

Journal of Applied Physics

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“…The spectra pertaining to the Gd-doped ZnO films grown at low P d (oxygendeficiency conditions) show a dominant green PL band at 495 nm (2.50 eV), attributed to V O [33][34][35][36]. Previous research has suggested that this green band in ZnO comes from complex defects, such as defects related to pairs of V O −Zn vacancies (V Zn ) [37] or associated with zinc interstitials (Zn i ) [38] or antisites (O Zn ) [39]. A sample grown under rich oxygen conditions (P d > 25 mTorr) shows a dominant red band emission centered at 690 nm as shown in Figure 3(b).…”

Section: Optical Propertiesmentioning

confidence: 99%

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

Roqan¹,

Aravindh²,

Singaravelu³

2016

Magnetic Materials

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The magnetic properties of Gd-doped ZnO films and nanostructures are important to the development of next-generation spintronic devices. Here, we elucidate the significant role played by Gd-oxygen-deficiency defects in mediating/inducing ferromagnetic coupling in in situ Gd-doped ZnO thin films deposited at low oxygen pressure by pulsed laser deposition (PLD). Samples deposited at higher oxygen pressures exhibited diamagnetic responses. Vacuum annealing was used on these diamagnetic samples (grown at a relatively high oxygen pressures) to create oxygendeficiency defects with the aim of demonstrating reproducibility of room-temperature ferromagnetism (RTFM). Samples annealed at oxygen environment exhibited superparamagnetism and blocking-temperature effects. The samples possessed secondary phases; Gd segregation led to superparamagnetism. Theoretical studies showed a shift of the 4f level of Gd to the conduction band minimum (CBM) in Gd-doped ZnO nanowires, which led to an overlap with the Fermi level, resulting in strong exchange coupling and consequently RTFM.

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“…In the early studies it was unambiguously attributed to copper impurities, 8 but strong evidence was later presented in favor of native defects such as V O or complex defect involving V O , Zn i , and O Zn . [9][10][11] Now, GL is generally accepted to be related to V O . In spite of numerous reports on the effects of DLs on optical and electrical properties of ZnO-based devices, there have been no satisfactory reports on the correlation between DLs and gas-sensing properties.…”

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confidence: 99%