Interface states and MWS polarization contributions to the dielectric response of low voltage ZnO varistor

2011 ◽  
Vol 37 (1) ◽  
pp. 207-214 ◽  
Author(s):  
C. Tsonos ◽  
A. Kanapitsas ◽  
D. Triantis ◽  
C. Anastasiadis ◽  
I. Stavrakas ◽  
...  
Keyword(s):  
Dielectric Response ◽  
Low Voltage ◽  
Interface States ◽  
Zno Varistor

La Doped Layered Structure Low-Voltage ZnO Varistor

2012 ◽  
Vol 512-515 ◽  
pp. 1263-1267
Author(s):  
Xing Gao ◽  
Guo You Gan ◽  
Li Hui Wang ◽  
Ji Kang Yan ◽  
Jian Hong Yi ◽  
...  
Keyword(s):  
Layered Structure ◽  
Low Voltage ◽  
Ion Concentration ◽  
Secondary Phases ◽  
Electrical Measurements ◽  
Leakage Currents ◽  
Epma Data ◽  
Zno Varistor ◽  
Current Voltage ◽  
La Doped

A novel fabricated technique, by feeding two sets of different ZnO formulations powder in a die by parts, molded only once to produce layered structure(including layer A and layer B) low-voltage ZnO varistor. The samples are examined by using energy dispersive X-ray spectroscopy (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and DC electrical measurements. EDS and EPMA data indicate that doped elements only exists in layer A, The results of SEM indicate that secondary phases are formed at grain boundaries in layer A, not found in layer B. It is found that the electrical properties of low-voltage varistor are improved without reducing thickness and changing energy absorption capabilities. The higher nonlinearity coefficients, lower breakdown fields and leakage currents of layered structure low-voltage ZnO varistor, as compared to those of ZnO varistor fabricated from the conventional route. The improved current-voltage properties are attributed to the band structure difference in both sides grains, due to the different ion concentration and species in both sides of grain boundary. Layered structure varistor also has more simpler prepared technology than multilayer chip varistor.

scholarly journals Exaggerated Grain Growth of ZnO in Low Voltage ZnO Varistor.

1994 ◽  
Vol 41 (2) ◽  
pp. 193-195
Author(s):  
Atsushi Iga ◽  
Masahiro Ito ◽  
Hideyuki Okinaka
Keyword(s):  
Grain Growth ◽  
Low Voltage ◽  
Zno Varistor

On the role of interface states in low-voltage leakage currents of metal–oxide–semiconductor structures

2002 ◽  
Vol 80 (24) ◽  
pp. 4597-4599 ◽  
Author(s):  
F. Crupi ◽  
C. Ciofi ◽  
A. Germanò ◽  
G. Iannaccone ◽  
J. H. Stathis ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Low Voltage ◽  
Interface States ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Leakage Currents ◽  
Semiconductor Structures

Influence of donor density in ZnO on ZnO–PrCoOx thin-film junctions: Role of O2 and Al dopant in varistors

1994 ◽  
Vol 9 (3) ◽  
pp. 669-673 ◽  
Author(s):  
Yoshihiko Yano ◽  
Yukihiko Shirakawa ◽  
Hisao Morooka
Keyword(s):  
Deep Level ◽  
Interface States ◽  
Clear Correlation ◽  
Zno Film ◽  
Donor Density ◽  
Zno Varistor ◽  
Capacitance Voltage ◽  
Single Grain ◽  
Transient Spectroscopy

ZnO/PrCoOx and ZnO/PrCoOx/ZnO junctions have been fabricated by sputtering as a model of a single grain boundary in a ceramic ZnO varistor. The relations between barrier parameters and varistor characteristics were investigated using voltage-current (V-I) capacitance-voltage (C-V), and deep-level transient spectroscopy (DLTS) measurements. The varistor voltage of the junctions increases as the donor density (ND) of the ZnO film decreases. The interface states vary according to the method of ZnO sputtering. A clear correlation has been established between the α value and the interface states. The highest α value is obtained when ND is ≃ 1018 cm−3, the interface level is 0.70 eV, and the breakdown voltage is 3–4 V. Oxygen is effective on control of ND in ZnO and the interface states. Al added as a dopant is also effective in terms of its ability to increase ND in ZnO. However, Al doping was found to degrade the interface states and increase the leakage current.

Interface states in ZnO varistor with Mn, Co, and Cu impurities

1994 ◽  
Vol 9 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Yoshihiko Yano ◽  
Yoshizo Takai ◽  
Hisao Morooka
Keyword(s):  
Transition Metals ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Interface States ◽  
Model Systems ◽  
Excess Oxygen ◽  
Molecular Orbital Calculations ◽  
Transition Metal Doping ◽  
Zno Varistor ◽  
Transient Spectroscopy

The interface states in ZnO with impurities of transition-metals, Mn, Co, and Cu, were investigated by the DLTS (deep-level transient spectroscopy) measurements in ZnO/PrCoOx/ZnO junctions as model systems of ZnO ceramic varistors and by the SCF-Xα-SW molecular orbital calculations using simplified cluster models. The DLTS signals, correlated to the doping of Mn and Co, are obtained with ZnO/PrCox/ZnO junctions. The signals correspond to the interface states due to the transition-metal doping. Xα calculations indicate that the interface states attributed to the doping of transition-metals, Mn, Co, and Cu, in ZnO are created between the valence band and the conduction band, which consist of transition-metals 3d character. The impurities of transition-metals affect interface states as well as the adsorbed excess oxygen.

scholarly journals Micro-Degradation Characteristics and Mechanism of ZnO Varistors under Multi-Pulse Lightning Strike

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2620
Author(s):  
Chunlong Zhang ◽  
Hongyan Xing ◽  
Chunying Li ◽  
Ran Cai ◽  
Dongbo Lv
Keyword(s):  
Boundary Layer ◽  
Grain Boundary ◽  
Distribution Systems ◽  
Pulse Current ◽  
Low Voltage ◽  
Grain Structure ◽  
Lightning Strike ◽  
Time Interval ◽  
Zno Varistor ◽  
Zno Varistors

In view of the problem that ZnO varistors are often subjected to thermal breakdown and deterioration due to lightning strikes in low-voltage power distribution systems, this article used a 8/20 µs multi-pulse surge current with a pulse time interval of 50 ms to perform shock experiments on ZnO varistors. SEM scanning electron microscope and an XRD diffractometer were used to analyze the structure of the grain boundary layer and the change of the crystalline phase material of ZnO varistor under the action of a multi-pulse current. The damage mechanism of ZnO varistor under the multi-pulse current was studied at the micro level. The results show that the average impact life of different types of ZnO varistor is significantly different. It was found that the types of trace elements and grain size in the grain boundary layer will affect the ability of ZnO varistor to withstand multi-pulse current. As the number of impulses increases, the grain structure of the ZnO varistor continues to degenerate. The unevenness of internal ion migration and the nonuniformity of the micro-grain boundary layer cause the local energy density to be too large and cause the local temperature rise to be too high, which eventually causes the internal grain boundary to melt through, and the local high temperature may cause the Bi element in the ZnO varistor to change in different crystal phases.

Dielectric response of piezoelectric ceramics at low voltage excitations

2008 ◽  
Vol 62 (25) ◽  
pp. 4173-4174 ◽  
Author(s):  
Sunil Sudhakaran ◽  
Kok Boon Chong ◽  
David Barrat ◽  
Asim K. Ray
Keyword(s):  
Dielectric Response ◽  
Low Voltage ◽  
Piezoelectric Ceramics
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