The mechanism of formation of interface barriers in ZnO:Mn ceramics

Nosenko, Valentyna; Korsunska, N.; Vorona, Igor; Stara, T.; Bondarenko, V. P.; Melnichuk, O.; Melnichuk, L.; Kryvko, Andriy; Маркевич, И. В.

doi:10.1007/s42452-020-2754-8

Cited by 8 publications

(10 citation statements)

References 16 publications

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“…Earlier, we have shown for the ZnO:Mn ceramics that oxygen adsorption plays a dominant role in barrier formation. [ 21 ] Indeed, in a similar experiment, the conductivity, after light‐off switching and relaxing, shows photoadditive contribution which remains increased relative to the initial conductivity measured in the darkness (Figure 9b, curves 1 and 3). This was explained by the fact that the desorption of oxygen leads to the disappearance of the near‐surface depletion region in the crystallites and corresponding barriers.…”

Section: Discussionmentioning

confidence: 57%

Effect of Milling of ZnO and MgO Powders On Structural, Optical, and Electrical Properties of (Mg,Zn)O Ceramics

Korsunska

Маркевич

Ponomaryov

et al. 2022

Physica Status Solidi (a)

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The effect of the milling of virgin ZnO and MgO powders on structural, optical, and electrical properties of Mg0.2Zn0.8O ceramics is studied. In all Mg0.2Zn0.8O ceramics, both cubic and hexagonal phases of solid solution are formed simultaneously. The hexagonal phase is represented by densely sintered grains that are doped with magnesium homogeneously. The crystallites of cubic phase of solid solution turn out to appear in large pores. The infrared reflection spectra show that the milling of intial powders does not affect free carrier concentration in hexagonal grains. It is found to be close to that of ZnO being determined by Zn interstials. For ceramics sintered from virgin powders, a decrease of direct current conductivity of Mg0.2Zn0.8O in comparison with that of pure ZnO occurres, which is being caused by the appearance of barriers, the nature of which may be ascribed to the fluctuations in the bandgap and/or electron concentration. For ceramics sintered from milled powders, an increase in DC conductivity of all samples is found and attributed to the formation of conductive channels along the grain boundaries via their enrichment in Zn and Mg due to mechanical stress. A chemical mapping of the ceramics supports this effect.

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Section: Discussionmentioning

confidence: 57%

Effect of Milling of ZnO and MgO Powders On Structural, Optical, and Electrical Properties of (Mg,Zn)O Ceramics

Korsunska

Маркевич

Ponomaryov

et al. 2022

Physica Status Solidi (a)

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“…33 The increase of Mnrelated phase content in the intergranural spaces is known to promote barrier formation in the sample. 9,12 In fact, as was shown in Ref. 12, the interface barrier formation in ZnO:Mn ceramics occurs via ambient oxygen adsorption on ZnO grain surfaces, which becomes possible due to the presence of a Mn-related layer that separates ZnO grains.…”

Section: Resultsmentioning

confidence: 88%

“…[5][6][7][8] However, in spite of extensive investigation of ZnO:Mn over the last decades, the influence of Mn distribution throughout ZnO grains and intergranular space on the electric properties of this material has not been clarified and controversial viewpoints are discussed. 5,9,11,12 Some authors state that the preferential Mn location at the grain boundaries is the reason for nonlinearity of CV characteristics. 9,12 At the same time in Ref.…”

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confidence: 99%

“…5,9,11,12 Some authors state that the preferential Mn location at the grain boundaries is the reason for nonlinearity of CV characteristics. 9,12 At the same time in Ref. 5 a homogeneous Mn distribution without segregation at the grain boundaries has been supposed and observed nonlinearity has been ascribed to the interaction of oxygen with native defects of ZnO.…”

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confidence: 99%

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Mn Distribution in ZnO:Mn Ceramics: Influence of Sintering Process and Thermal Annealing

Маркевич¹,

Vorona²,

Nosenko³

et al. 2020

ECS J. Solid State Sci. Technol.

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Manganese spatial distribution in ZnO:Mn ceramics (0.1–5 at.% Mn) sintered at 1100 °C in air has been investigated using Electron paramagnetic resonance (EPR), micro-Raman and Diffuse reflectance spectroscopy. The Raman and EPR spectra show that concentration of Mn incorporated in ZnO grains decreases from the surface of ceramic sample to its depth. Mn distribution in ZnO grains is also inhomogeneous. The concentration of Mn on Zn site centers (MnZn2+) evaluated from the EPR data is found to be lower than the Mn content in the charge indicating a large amount of Mn remains in the intergranular spaces. Thermostimulated Mn redistribution between the ZnO grain and the intergranural spaces have been observed under post sintering annealing. The influence of ZnO native donors on MnZn2+ center formation is found. It is supposed that this effect is due to interaction of Mn with interstitial zinc. The impact of native donor concentration on current-voltage characteristics of ZnO:Mn ceramics is demonstrated. The influence of Mn distribution on varistor characteristic is discussed.

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“…It is worth to point out that in pure ZnO ceramics (that is the other type of polycrystalline ZnO) impedance measurements did not reveal barriers at grain boundaries [65]. This can be explained by the negligible oxygen adsorption on ZnO grain surface because of hardly possible oxygen diffusion along the grain boundaries in ceramic bulk [66]. However, the production of ceramic samples requires their pressing and subsequent sintering at high temperatures.…”

Section: Direct Dark Current Measurementsmentioning

confidence: 97%

Optical, structural and electrical characterization of pure ZnO films grown on p-type Si substrates by radiofrequency magnetron sputtering in different atmospheres

Melnichuk

Venger

et al. 2020

Semicond. Sci. Technol.

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ZnO films were grown on p-type Si substrates by radio-frequency magnetron sputtering of ZnO target in pure argon or mixed argon-oxygen plasma and were investigated using atomic force microscopy, spectroscopic ellipsometry, Fourier-transformed infrared spectroscopy and electrical methods. It was observed that the films grown in argon plasma had large surface roughness which increases with the rise of deposition time. The lateral size of ZnO columns showed similar dependence on deposition parameters as the roughness. Contrary to this, the films produced in argon-oxygen plasma were found to be smoother and denser having thinner ZnO columns. These films also demonstrated an abrupt absorption band-gap edge that is the evidence of better crystalline quality of these films (the lower number of native point and elongated defects). Plasmon-phonon interaction in ZnO films as well as the effect of the plasmon system of Si substrate on this interaction was considered. The theoretical approach used for the fitting of specular infrared reflection spectra allowed determining concentration and mobility of free carriers as well as conductivity of ZnO films. It was found that the films grown in pure argon plasma demonstrated a higher concentration and a smaller mobility of free carriers in the comparison with the corresponding parameters of the films grown in argon-oxygen mixed plasma. The direct resistivity measurements show the essentially higher values compared with the values estimated from IR reflection spectra. The possible reasons of this difference are discussed. The utility of infrared reflection spectroscopy for the non-destructive analysis of electro-physical properties of polycrystalline films was shown.

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The mechanism of formation of interface barriers in ZnO:Mn ceramics

Cited by 8 publications

References 16 publications

Effect of Milling of ZnO and MgO Powders On Structural, Optical, and Electrical Properties of (Mg,Zn)O Ceramics

Effect of Milling of ZnO and MgO Powders On Structural, Optical, and Electrical Properties of (Mg,Zn)O Ceramics

Mn Distribution in ZnO:Mn Ceramics: Influence of Sintering Process and Thermal Annealing

Optical, structural and electrical characterization of pure ZnO films grown on p-type Si substrates by radiofrequency magnetron sputtering in different atmospheres

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