Abrupt and tunable quenching of photoluminescence in ZnO

McNamara, J. D.; Albarakati, Nahla Mubarak; Reshchikov, M. A.

doi:10.1016/j.jlumin.2016.06.013

Cited by 19 publications

(16 citation statements)

References 33 publications

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“…The optical properties of Li in ZnO have also been studied extensively. EPR [13,14] and optically detected magnetic resonance studies [9,15,16] have established a correlation between the Li 0 Zn magnetic resonance line and a broad orange luminescence (OL) band with a maximum at 1.95 eV at 10 K [17][18][19]. The OL band is normally present in the photoluminescence (PL) spectrum of hydrothermally (HT) grown ZnO [18] crystals, which contain Li impurities with concentrations in the (1-5) × 10 17 cm −3 range [20].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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Zn substitutional lithium (Li Zn) and sodium (Na Zn) acceptors and their complexes with common donor impurities (Al Zn , H i , and H O) in ZnO have been studied using hybrid functional calculations. The results show that the complexes are not exclusively charge neutral, but rather exhibit a thermodynamic (+/0) transition level close to the valence band maximum. The positive charge states are associated with a polaronic defect state, similar to those of the well-studied charge-neutral isolated acceptors. This incomplete passivation has profound consequences for the optical properties of the complexes. Indeed, electron transitions from the conduction band minimum to the (+/0) transition level of the complexes result in broad luminescence bands that are blueshifted with respect to those originating from the isolated acceptors. Such complexes are proposed as a potential defect origin of the green luminescence observed at the high-energy side of the orange luminescence band (caused by Li Zn) in hydrothermally grown ZnO. This prediction is supported by experimental photoluminescence and secondary ion mass spectrometry data on a hydrothermally grown ZnO sample. We have also explored how the parameters controlling the fraction and screening of exchange in the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional influence the results by comparing two parametrization approaches: (i) the conventional one where the exchange fraction is adjusted to reproduce the experimental band gap, and (ii) tuning both parameters in order to also comply with the generalized Koopmans theorem (gKT). Interestingly, these approaches were found to yield similar results.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…Li acceptors give rise to the broad yellow PL band [35], due to the transition of an electron from the conduction band (CB) (or a shallow donor) to the acceptor level. The previous research has demonstrated that there are two processes that lead to yellow PL, excitation from the Liacceptor and excitation from the valence band (VB) [36,37]. The fitted-peak emission line at 627.2 nm corresponds to the RL, the peak-3 could be assigned to the transitions between a shallow donor (at low temperature) or the conduction band (at higher temperature) and the Li zn acceptor [37].…”

Section: Resultsmentioning

confidence: 98%

Enhancement of multi-photon Raman scattering and photoluminescence emission from Li-doped ZnO nanowires

et al. 2019

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Uniform Li-doped ZnO nanowires have been fabricated by thermal evaporation method. The ZnO formation and the Li incorporation have been discussed and the formation path of preparation products has also been explained in terms of the stability of Zn and Li vapor in an aerobic atmosphere. The strongest vibration mode at 437.2 cm −1 in the multi-photon Raman scattering of the as-prepared products at room temperature indicates that the Li-doped ZnO nanowires still keep the hexagonal (wurtzite) structure. Raman spectra of Li-doped ZnO with different doping concentrations confirm that the variation of Raman peaks in the range of 550 cm −1 ∼650 cm −1 is caused by the doping of lithium. The photoluminescence property at room temperature shows a blue-shift compared with undoped ZnO in the ultraviolet region. The Gauss fitting analyzed results indicate that the broad-band is composed of one green luminescence (GL) band, one yellow luminescence (YL) band, and one red luminescence (RL) band, respectively. The GL (2.447 eV) could be attributed to the singly ionized oxygen vacancies. The origin of the YL (2.245 eV) could be assigned to the transition of an electron from the conduction band (or a shallow donor) to the Li acceptor level. The RL (1.977 eV) could be assigned to the transitions between a shallow donor (at low temperature) or the conduction band (at higher temperature). Furthermore, the luminescence spectra at low temperature confirm the increase of defect levels like oxygen vacancies.

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“…The DLE was composed of the orange luminescence at ~2.1 eV and of the green luminescence at ~2.47 eV. The origin of the orange emission band is generally attributed to different sources such as ionized oxygen interstitials or Li impurities [42][43][44]. The origin of the green luminescence was To prove the conclusions from other characterization techniques, the seed layers preheated at 400 • C and annealed in the air at 600 • C were further investigated by ACOM-TEM (ASTAR) ( Figure 6).…”

Section: Resultsmentioning

confidence: 99%

“…The DLE was composed of the orange luminescence at~2.1 eV and of the green luminescence at~2.47 eV. The origin of the orange emission band is generally attributed to different sources such as ionized oxygen interstitials or Li impurities [42][43][44]. The origin of the green luminescence was assigned to the transitions in which oxygen vacancies, oxygen interstitials, or extrinsic defects such as Cu are involved [45,46].…”

Section: Resultsmentioning

confidence: 99%

Highly Textured Seed Layers for the Growth of Vertically Oriented ZnO Nanorods

et al. 2019

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One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are at the forefront of this research. Vertically oriented ZnO nanorods with uniform physical properties require high-quality seed layers with a narrow size distribution of the crystallites, strong c-axis orientation, and low surface roughness and porosity. It has been shown that high quality seed layers can be prepared by the sol–gel process. The sol–gel process involves three essential steps: preparation of the sol, its deposition by dip coating, and thermal treatment comprising preheating and annealing. We put emphasis on the investigation of the heat treatment on the properties of the seed layers and on the vertical alignment of the nanorods. It was demonstrated that for the vertical alignment of the nanorods, the preheating step is crucial and that the temperatures reported in the literature have been too low. With higher preheating temperatures, conditions for the vertical alignment of the nanorods were achieved in both investigated annealing atmospheres in air and in argon.

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Abrupt and tunable quenching of photoluminescence in ZnO

Cited by 19 publications

References 33 publications

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

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

Enhancement of multi-photon Raman scattering and photoluminescence emission from Li-doped ZnO nanowires

Highly Textured Seed Layers for the Growth of Vertically Oriented ZnO Nanorods

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