Quantitative Icts Measurement of Interface States at Grain Boundaries in ZnO Varistors

1997 ◽  
Vol 500 ◽  
Author(s):  
K. Mukae ◽  
A. Tanaka
Keyword(s):  
Grain Boundaries ◽  
Interface States ◽  
Zno Varistors ◽  
Single Grain ◽  
Doped Zno ◽  
Transient Spectroscopy ◽  
Er Doped ◽  
Capacitance Transient ◽  
Rare Earth Doped ◽  
Density Of Interface States

ABSTRACTIsothermal capacitance transient spectroscopy(ICTS) measurement is applied to ZnO:Pr varistors. A simple peak corresponding to the interface states at grain boundaries was obtained and the energy level of the interface states revealed to be monoenergetic and located around 0.9eV below the conduction band. The cross section was calculated as around 10−14 cm2. Quantitative treatment of the ICTS intensity in relation to the density of interface states at grain boundaries was established. The density of interface states was obtained from the linear relation between ICTS intensity and reciprocal carrier density(ND). According to experiments on series of rare-earth doped ZnO varistors, the interface states of Pr, Tb or Nd doped ZnO varistors had higher density of states than La or Er doped varistors. Moreover, application of ICTS measurement to single grain boundary using microelectrodes revealed that higher density of interface states gave higher nonlinearity in I-V characteristics.

scholarly journals Charge transport mechanism in copper phthalocyanine thin films with and without traps

RSC Advances ◽  
2017 ◽  
Vol 7 (86) ◽  
pp. 54911-54919 ◽  
Author(s):  
Varsha Rani ◽  
Akanksha Sharma ◽  
Pramod Kumar ◽  
Budhi Singh ◽  
Subhasis Ghosh
Keyword(s):  
Thin Films ◽  
Charge Transport ◽  
Grain Boundaries ◽  
Transport Mechanism ◽  
Copper Phthalocyanine ◽  
Organic Thin Films ◽  
Interface States ◽  
Charge Transport Mechanism ◽  
Density Of Interface States

We investigate the charge transport mechanism in copper phthalocyanine thin films with and without traps. We find that the density of interface states at the grain boundaries can decide the mechanism of charge transport in organic thin films.

Electronic Structure of Grain Boundaries and Interfaces in Polycrystalline Zinc Oxide

1981 ◽  
Vol 5 ◽  
Author(s):  
M. H. Sukkar ◽  
H. L. Tuller ◽  
K. H. Johnson
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Scattered Wave ◽  
Theoretical Models ◽  
Interface States ◽  
Molecular Orbital Calculations ◽  
Conduction Bands ◽  
Consistent Field ◽  
Self Consistent Field ◽  
Zno Varistors

ABSTRACTPreliminary theoretical models for the electronic structure of grain boundaries and interfaces in polycrystalline ZnO have been constructed on the basis of self-consistent-field X-alpha scattered-wave (SCF-Xα-SW) cluster molecular-orbital calculations. The disposition and character of the interface states, relative to the valence and conduction bands of the otherwise perfect crystalline material, have been studied for clusters representing coordinatively unsaturated Zn surface sites and molecular O2 chemisorption thereon. The possible effects of the resuiting interface states on electron transport at grain boundaries in ZnO varistors have been addressed.

Characterization of Single Grain Boundaries in a Bi-Doped ZnO Varistor Using a Focused Ion Beam System

2000 ◽  
Vol 39 (Part 1, No. 7B) ◽  
pp. 4493-4496 ◽  
Author(s):  
Junji Tanimura ◽  
Osamu Wada ◽  
Hiroshi Kurokawa ◽  
Naomi Furuse ◽  
Masahiro Kobayashi
Keyword(s):  
Grain Boundaries ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Zno Varistor ◽  
Beam System ◽  
Single Grain ◽  
Doped Zno

Evaluation of Interface States in ZnO Varistors by Spectral Analysis of Deep Level Transient Spectroscopy

1999 ◽  
Vol 38 (Part 1, No. 2A) ◽  
pp. 899-900 ◽  
Author(s):  
Yasuhiro Ohbuchi ◽  
Junya Yoshino ◽  
Yoichi Okamoto ◽  
Jun Morimoto
Keyword(s):  
Spectral Analysis ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Interface States ◽  
Zno Varistors ◽  
Transient Spectroscopy

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.

Chemical State Analysis of Grain Boundaries of Bi2O3-Doped ZnO Varistors

1993 ◽  
Vol 126-128 ◽  
pp. 109-112
Author(s):  
Shun Ichiro Tanaka ◽  
K. Takahashi ◽  
C. Akita ◽  
Hajime Haneda ◽  
M. Tanaka
Keyword(s):  
Grain Boundaries ◽  
Chemical State ◽  
Zno Varistors ◽  
Doped Zno ◽  
State Analysis

Characterization of interface states in (Sr, Ca)TiO3−x based ceramics by ICTS analysis

1991 ◽  
Vol 6 (6) ◽  
pp. 1346-1349 ◽  
Author(s):  
Yoshitaka Nakano
Keyword(s):  
Interface States ◽  
Oxidation Temperature ◽  
Trap Level ◽  
Ohmic Conduction ◽  
Chemisorbed Oxygen ◽  
Transient Spectroscopy ◽  
Capacitance Transient ◽  
Isothermal Capacitance Transient Spectroscopy ◽  
Good Agreement

Isothermal capacitance transient spectroscopy measurements were performed to study the reoxidizing induced change in interface states in (Sr, Ca)TiO3−x based ceramics. A discrete acceptor type trap level was detected with reoxidation below the oxidation temperature of grain surfaces, but two deep levels were detected with reoxidation above this temperature. These ICTS results are in good agreement with the previous report with the DLTS measurements. These interface states are considered to originate from chemisorbed oxygen (O2−, O−) on grain surfaces. The O− and O2− chemisorption levels contribute to the non-ohmic conduction with reoxidizing anneals below and above the oxidation temperature, respectively.

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