Grain Boundaries in Crystallized Silicon Thin Films

1981 ◽  
Vol 5 ◽  
Author(s):  
N. M. Johnson ◽  
D. K. Biegelsen ◽  
M. D. Moyer
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Secondary Ion Mass Spectrometry ◽  
Bulk Diffusion ◽  
Silicon Thin Films ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Silicon Islands ◽  
Device Operation ◽  
Secondary Ion

ABSTRACTThe presence of residual grain boundaries in laser-crystallized thin films of silicon necessitates an understanding of their properties and effects on device operation. In CW laser crystallized silicon islands, lateral p-n junction diodes have been used to evaluate the following: (1) enhanced arsenic diffusion along grain boundaries, (2) current-voltage characteristics, and (3) effects of hydrogenation on diode operation. To study the process of hydrogen passivation, deuterium has been used as a readily identifiable isotope which duplicates hydrogen chemistry. From secondary-ion mass spectrometry, diffusion of deuterium in single-crystal and polycrystalline silicon at low temperatures (e.g., 350 C) clearly demonstrates that grain-boundary diffusion dominates bulk diffusion.

First Study of Oxygen Diffusion in a ZnO - Based Commercial Varistor

2009 ◽  
Vol 289-292 ◽  
pp. 339-345
Author(s):  
Antônio Claret Soares Sabioni ◽  
Antônio Márcio J.M. Daniel ◽  
Renaud Metz ◽  
Anne Marie Huntz ◽  
François Jomard
Keyword(s):  
Grain Boundaries ◽  
Oxygen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Bulk Diffusion ◽  
Simple Explanation ◽  
Exchange Method ◽  
Microstructural Parameters ◽  
Secondary Ion ◽  
Oxygen Tracer ◽  
Diffusion Profiles

Oxygen diffusion coefficients were determined in a commercial ZnO-based varistor by means of the gas-solid exchange method using the isotope 18O as the oxygen tracer. The diffusion annealings were performed at 892, 942, 992 and 1092oC, in an Ar + 18O2 atmosphere under an oxygen partial pressure of 0.2 atm. After the diffusion annealings, the 18O diffusion profiles were established by secondary ion mass spectrometry (SIMS). The results show an increase of the oxygen diffusion in the varistor, both in bulk and in grain boundaries, when compared to the oxygen diffusion in undoped ZnO. The increase of the oxygen bulk diffusion in the varistor agrees with an interstitial mechanism for the oxygen diffusion. The results also show that the grain boundary is a fast path for the oxygen diffusion in the varistor. However, the oxygen diffusion in the grain boundaries of the varistor seems to depend on several chemical and microstructural parameters and does not allow a simple explanation.

Interfacial Reactions Between Metal Thin Films and p-GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
J.T. Trexler ◽  
S.J. Miller ◽  
P.H. Holloway ◽  
M.A. Khan
Keyword(s):  
Thin Films ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Doping Concentration ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Region ◽  
Metal Thin Films ◽  
Current Voltage ◽  
P Type ◽  
Secondary Ion

ABSTRACTThe reactions between Au, Au/Ni and Au/C/Ni thin films on p-GaN have been studied using current-voltage (I-V) measurements, Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS). The metallization schemes consisted of ≈2000Ǻ sputtered Au, 1000Ǻ Au/500Ǻ Ni, and 1000Ǻ Au/100Ǻ C/500Ǻ Ni electron beam evaporated. The Au/Ni metallization scheme is of particular interest since it is the basis for the most commonly used ohmic p-type contacts for blue GaN LED’s. Au does not decompose the GaN matrix, while Ni has been shown to react with GaN above a temperature of 400° C for times longer than 5 minutes. Upon decomposition of the GaN by Ni, incorporation of C at the metal/GaN interface occurred. It is believed that a regrowth of GaN occurred, with the surface region being doped with C. Attempts at increasing this doping concentration by introducing an interfacial C layer were not successful.

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.

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.

Preparation and Electrical Characteristics of (100), (111), and Randomly Oriented PZT Thin Films

1994 ◽  
Vol 361 ◽  
Author(s):  
Chang Jung Kim ◽  
Dae Sung Yoon ◽  
Joon Sung Lee ◽  
Chaun Gi Choi ◽  
Won Jong Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Hysteresis Loops ◽  
Test System ◽  
Electrical Characteristics ◽  
Pzt Thin Films ◽  
Pole Figures ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Drying Conditions

ABSTRACTThe (100), (111) and randomly oriented PZT thin films were fabricated on Pt/Ti/Coming 7059 glass using sol-gel method. The thin films having different orientation were fabricated by different drying conditions for pyrolysis. The preferred orientations of the PZT thin films were observed using XRD, rocking curves, and pole figures. The microstructures were investigated using SEM. The hysteresis loops and capacitance-voltage characteristics of the films were investigated using a standardized ferroelectric test system. The dielectric constant and current-voltage characteristics of the films were investigated using an impedance analyzer and pA meter, respectively. The films oriented in a particular direction showed superior electrical characteristics to the randomly oriented films.

Photoconductivity of Nanocomposite MEH-PPV: TiO2 Thin Films

2011 ◽  
Vol 13 ◽  
pp. 87-92 ◽  
Author(s):  
M.S.P Sarah ◽  
F.S. Zahid ◽  
M.Z. Musa ◽  
U.M. Noor ◽  
Z. Shaameri ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Surface Morphology ◽  
Spin Coating ◽  
Glass Substrate ◽  
Spin Coating Technique ◽  
Coating Technique ◽  
Current Voltage ◽  
Current Voltage Characteristics

The photoconductivity of a nanocomposite MEH-PPV:TiO2 thin film is investigated. The nanocomposite MEH-PPV:TiO2 thin film was deposited on a glass substrate by spin coating technique. The composition of the TiO2 powder was varied from 5 wt% to 20 wt% (with 5 wt% interval). The concentration of the MEH-PPV is given by 1 mg/1 ml. The current voltage characteristics were measured in dark and under illumination. The photoconductivity showed increment in value as the composition of the TiO2 is raised in the polymer based solution. The absorption showed augmentation as the amount of TiO2 is increased. The escalation of the current voltage is then supported by the results of surface morphology.

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