Non-Ohmic Properties of ZnO-Rare Earth Metal Oxide-Co<sub>3</sub>O<sub>4</sub>Ceramics

Mukae, Kazuo; Tsuda, Kouichi; Nagasawa, Ikuo

doi:10.1143/jjap.16.1361

Cited by 240 publications

(90 citation statements)

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“…Doping other elements can be considered as one of the effective methods to stabilize these defects. For ZnO based varistor materials, Co dopant is known as one of the key additives to obtain/improve non-linear I -V characteristics in ZnO varistor [1,2]. Although Co dopant itself cannot be an acceptor [24,28,29], it has been proposed that Co dopant generate DSB by the stabilization of O 00 i [30,31] or V 00…”

Section: Discussionmentioning

confidence: 99%

Non-linear current–voltage characteristics related to native defects in SrTiO₃ and ZnO bicrystals

Satô

Tanaka

Oba

et al. 2003

Science and Technology of Advanced Materials

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SrTiO 3 and ZnO bicrystals with various types of boundaries were fabricated in order to examine their current -voltage characteristics across single grain boundaries. Their grain boundary structures were also investigated by high-resolution transmission electron microscopy. In Nb-doped SrTiO 3 , electron transport behaviors depend on the type of boundaries. Random type boundaries exhibit highly non-linear current-voltage characteristics, while low angle boundaries show a slight non-linearity. On the contrary, undoped ZnO does not exhibit nonlinear current -voltage characteristics in any type of boundaries including random ones. It is suggested that the differences observed in current-voltage properties between the two systems are mainly due to the difference in the accumulation behavior of acceptor-like native defects at grain boundaries. A clear non-linearity is obtained by means of Co-doping even for the highly coherent S1 boundary in a ZnO bicrystal. This is considered to result from the production of acceptor-like native defects by Co-doping. q

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Section: Discussionmentioning

confidence: 99%

Non-linear current–voltage characteristics related to native defects in SrTiO₃ and ZnO bicrystals

Satô

Tanaka

Oba

et al. 2003

Science and Technology of Advanced Materials

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“…[1][2][3] The nonlinearity is attributed to the double Schottky barriers that originate from the formation of acceptor-type states at the interfaces between donor-rich grains. 4,5) Although the interfacial electronic states have been intensively investigated because of the importance in the nonlinear behavior, [6][7][8][9][10][11][12][13] the explicit origin still remains open.…”

Section: Introductionmentioning

confidence: 99%

“…3,18) Therefore, Co impurities should play important roles in the formation of the interfacial electronic states as well as excessive oxygen. However, it is not clear whether Co impurities are related to the interface structure at an electronic level.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Calculations of Co Impurities and Native Defects in ZnO

et al. 2002

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First-principles plane-wave pseudopotential calculations have been conducted to investigate Co impurities and native defects associated with oxygen excess in ZnO. The electronic states and formation energies are evaluated using the total energies of supercells. The electronic states indicate that Co impurities are donor-like, while native defects associated with oxygen excess are acceptor-like. Among the native defects, Zn vacancies are likely to be a dominant species in view of the much lower formation energy than those of the others. Calculations for Co impurity-Zn vacancy complexes imply that Co impurities stabilize Zn vacancies and hence oxygen excess in their vicinities. This is suggested to be a role of Co impurities at grain boundaries in ZnO varistor ceramics.

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“…[2][3][4][5][6][7] However, there is still room for improvement and new applications. In particular, surge filter technology is important for low-voltage applications.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of ZnO/Glass/ZnO Structures Showing Highly Nonlinear Current-Voltage Characteristics

et al. 2009

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As part of an effort to develop low-voltage surge filters, zinc oxide (ZnO) bicrystals were investigated to clarify the electronic state of grain boundaries in ZnO varistors. The varistors had a ZnO/glass/ZnO-type sandwich structure, and the interfacial glass layer was composed of oxide glass of the Bi-B-O system. A highly nonlinear current-voltage relationship was obtained for a sandwich structure composed of Co-doped single crystal ZnO, and the current through the junction was proportional to roughly the 30th power of the bias voltage at the breakdown stage. In contrast, the junction using undoped single crystal ZnO showed insignificant nonlinearity. Dielectric measurements revealed that a double-sided depletion layer was formed at the interface and the high nonlinearity was ascribed to the corresponding potential barrier formed at the interface.

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Non-Ohmic Properties of ZnO-Rare Earth Metal Oxide-Co₃O₄Ceramics

Cited by 240 publications

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Non-linear current–voltage characteristics related to native defects in SrTiO₃ and ZnO bicrystals

Non-linear current–voltage characteristics related to native defects in SrTiO₃ and ZnO bicrystals

First-Principles Calculations of Co Impurities and Native Defects in ZnO

Synthesis and Characterization of ZnO/Glass/ZnO Structures Showing Highly Nonlinear Current-Voltage Characteristics

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Non-Ohmic Properties of ZnO-Rare Earth Metal Oxide-Co3O4Ceramics

Cited by 240 publications

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Non-linear current–voltage characteristics related to native defects in SrTiO3 and ZnO bicrystals

Non-linear current–voltage characteristics related to native defects in SrTiO3 and ZnO bicrystals

First-Principles Calculations of Co Impurities and Native Defects in ZnO

Synthesis and Characterization of ZnO/Glass/ZnO Structures Showing Highly Nonlinear Current-Voltage Characteristics

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Product

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Non-Ohmic Properties of ZnO-Rare Earth Metal Oxide-Co₃O₄Ceramics

Non-linear current–voltage characteristics related to native defects in SrTiO₃ and ZnO bicrystals

Non-linear current–voltage characteristics related to native defects in SrTiO₃ and ZnO bicrystals