Current–voltage characteristics of grain boundaries in polycrystalline Sr-doped LaGaO3

2012 ◽  
Vol 14 (25) ◽  
pp. 9047 ◽  
Author(s):  
Chien-Ting Chen ◽  
Kwanghoon Choi ◽  
Sangtae Kim
Keyword(s):  
Grain Boundaries ◽  
Current Voltage ◽  
Current Voltage Characteristics

Grain Boundary Atomic Structures in SrTiO3 and BaTiO3

2007 ◽  
Vol 558-559 ◽  
pp. 851-856 ◽  
Author(s):  
Takahisa Yamamoto ◽  
Teruyasu Mizoguchi ◽  
S.Y. Choi ◽  
Yukio Sato ◽  
Naoya Shibata ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Annealing Temperature ◽  
Unit Length ◽  
Rate Dependency ◽  
Atomic Structures ◽  
Current Voltage ◽  
Single Grain ◽  
Current Voltage Characteristics ◽  
Theoretical Results

SrTiO3 bicrystals with various types of grain boundaries were prepared by joining two single crystals at high temperature. By using the bicrystals, we examined their current-voltage characteristics across single grain boundaries from a viewpoint of point defect segregation in the vicinity of the grain boundaries. Current-voltage property in SrTiO3 bicrystals was confirmed to show a cooling rate dependency from annealing temperature, indicating that cation vacancies accumulate due to grain boundary oxidation. The theoretical results obtained by ab-initio calculation clearly showed that the formation energy of Sr vacancies is the lowest comparing with Ti and O vacancies in oxidized atomosphere. The formation of a double Schottky barrier (DSB) in n-type SrTiO3 is considered to be closely related to the accumulation of the charged Sr vacancies. Meanwhile, by using three types of low angle boundaries, the excess charges related to one grain boundary dislocation par unit length was estimated. In this study, we summarized our results obtained in our group.

Effects of Grain Boundaries in Amorphous/Multicrystalline Silicon Heterojunction Photovoltaic Cells

2004 ◽  
Vol 836 ◽  
Author(s):  
M. Farrokh Baroughi ◽  
S. Sivoththaman
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Dark Current ◽  
Spectral Response ◽  
Simulation Software ◽  
Multicrystalline Silicon ◽  
Consistent Difference ◽  
Photovoltaic Properties ◽  
Current Voltage ◽  
Current Voltage Characteristics

ABSTRACTSpectral response and dark current-voltage characteristics of heterojunctions are used to investigate grain boundary degradation in photovoltaic properties of a-Si/mc-Si heterojunction solar cells. Measured spectral response inside the grain and on the grain boundary shows small but consistent QE degradation due to minority carrier recombination at the grain boundaries. No consistent difference is observed in dark current-voltage characteristics because of large diode area and periphery leakage current in the employed heterojunction diodes. Comparing measurement results and results from device modeling using the simulation software Medici, a recombination velocity of 4900 cm/sec is found at the grain boundaries of employed multicrystalline silicon wafer. The modeling and experimental results can also be used to define an effective grain area that serves as a measure of grain boundary recombination and the influence of grain size.

Current-voltage characteristics of ultrafine-grained ferroelectric Pb(Zr, Ti)O3 thin films

1994 ◽  
Vol 9 (6) ◽  
pp. 1484-1498 ◽  
Author(s):  
H. Hu ◽  
S.B. Krupanidhi
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
High Resistivity ◽  
Ultrafine Grained ◽  
Current Voltage ◽  
Electrode Interface ◽  
Current Voltage Characteristics ◽  
Homogeneous Media ◽  
Limited Conduction

Room-temperature current-voltage dependence of ultrafine-grained ferroelectric Pb(Zr, Ti)O3 thin films has been investigated. Both strong varistor type behavior and space charge limited conduction (SCLC) were observed. Differences in the current-voltage characteristics are attributed to differences in the nature of the grain boundaries resulting from variations in processing conditions. The strong varistor type behavior is believed to be due to the presence of highly resistive grain boundaries and thus may be termed grain boundary limited conduction (GBLC). A double-depletion-layer barrier model is used to describe the origin of high resistivity of the grain boundaries. It is suggested that the barrier height varies significantly with the applied field due to the nonlinear ferroelectric polarization, and that the barrier is overcome by tunneling at sufficiently high fields. In some other cases, the resistivity of the grain boundaries is comparable to that of the grains, and therefore the intrinsically heterogeneous films degenerate into quasi-homogeneous media, to which the SCLC theory is applicable. As such, a unified grain boundary modeling reconciles different types of conduction mechanisms in the ultrafine-grained ferroelectric thin films. This grain boundary modeling also well accounts for some other dc-related phenomena observed, including abnormal current-voltage dependencies, remanent polarization effect, electrode interface effect, and unusual charging and discharging transients. In addition, many other electrical properties of the ferroelectric films may be better understood by taking the effect of grain boundaries into account.

A linear diffusion model for ion current across blocking grain boundaries in oxygen-ion and proton conductors

2014 ◽  
Vol 16 (28) ◽  
pp. 14961-14968 ◽  
Author(s):  
Seong K. Kim ◽  
Sergey Khodorov ◽  
Igor Lubomirsky ◽  
Sangtae Kim
Keyword(s):  
Grain Boundaries ◽  
Diffusion Model ◽  
Solid Electrolytes ◽  
Proton Conductors ◽  
Ion Current ◽  
Linear Diffusion ◽  
Oxygen Ion ◽  
Current Voltage ◽  
Current Voltage Characteristics

We demonstrate the applicability of the linear diffusion model recently proposed for the current–voltage characteristics of grain boundaries in solid electrolytes.

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