Defect formation mechanism causing increasing defect density during decreasing implant dose in low-dose SIMOX

2002 ◽  
Author(s):  
J.D. Lee ◽  
J.C. Park ◽  
S. Krause ◽  
P. Roitman
Keyword(s):  
Formation Mechanism ◽  
Low Dose ◽  
Defect Formation ◽  
Defect Density

The Defect Formation Mechanism Associated with Low Dose Implants into Si Fin Structures

2018 ◽  
Author(s):  
Kevin Jones ◽  
Emily Turner ◽  
Jae Young Lee ◽  
Hans van Meer ◽  
Naushad Variam ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Low Dose ◽  
Defect Formation

Defect Formation Mechanism During PECVD of a-Si:H

1997 ◽  
Vol 467 ◽  
Author(s):  
Keiji Maeda ◽  
Ikurou Umezu
Keyword(s):  
Formation Mechanism ◽  
Urbach Energy ◽  
Defect Formation ◽  
Defect Density ◽  
Reaction Energy ◽  
Mobility Edge ◽  
Weak Bond ◽  
Bond Density ◽  
Extra Energy ◽  
Staebler Wronski Effect

ABSTRACTDefect formation mechanism in a-Si:H during PECVD at substrate temperature below 250°C is considered to be breaking of weak bonds in the Urbach tail. To break weak bonds, an extra energy is necessary. This energy is supplied by the reaction energy of SiH3 precursor at the growing surface incorporating SiH2 into the network. The defect density is experimentally shown to be proportional to a product of the energy supply frequency, i.e., SiH2 density, and the weak bond density which is obtained by the Urbach energy. By analysis using the configurational coordinate diagram the energy level of the broken weak bond is determined to be 0.2 eV above the valence band mobility edge. There is similarity of the defect formation mechanism during deposition to that of the Staebler-Wronski effect.

scholarly journals Beta Fleck formation in Titanium Alloys

2020 ◽  
Vol 321 ◽  
pp. 10001
Author(s):  
K. Kelkar ◽  
A Mitchell
Keyword(s):  
Titanium Alloys ◽  
Formation Mechanism ◽  
Defect Formation ◽  
Melting Rate ◽  
Vacuum Arc ◽  
Formation Mechanisms ◽  
Alloy Development ◽  
Vacuum Arc Remelting ◽  
Freckle Formation ◽  
Nickel Base

Beta fleck is a troublesome segregation defect in many titanium alloys. It has previously been investigated by several authors and appears to have two formation mechanisms, one similar to that of “freckle” in steels and nickel-base alloys, the other arising in the “crystal rain” effect seen in conventional steel ingots. The freckle defect has been extensively studied and several theories developed to account for its formation in both remelted ingots and directional castings. In this work we compare the findings of investigations into the nickel-base freckle formation mechanism to similar conditions in the vacuum arc remelting of titanium alloys. We find that there are strong similarities between the beta fleck formation conditions and the parameters related to the Rayleigh Number criterion for freckle formation. In particular, the dendritic solidification parameters and the density dependence on segregation coefficients both fit well with the conditions proposed to characterise freckle formation. The second formation mechanism arises in the columnar to equiax transition in solidification. The condition for the avoidance of the defect in the two cases is the shown to be the same, namely the use of a very low VAR melting rate, but that it is unlikely to be 100% successful in preventing defect formation. We propose that the techniques presently in use for alloy development in the superalloy field through optimising the composition for minimum sensitivity to freckle formation should be applied to the formulation of future titanium alloys; also that attention should be paid to developing the PAM process to provide suitable solidification conditions for defect absence in a final ingot.

Effects of nano-copper particles on the properties of Sn58Bi composite solder pastes

2017 ◽  
Vol 34 (1) ◽  
pp. 40-44 ◽  
Author(s):  
Hao Zhang ◽  
Yang Liu ◽  
Fenglian Sun ◽  
Gaofang Ban ◽  
Jiajie Fan
Keyword(s):  
Formation Mechanism ◽  
Composite Solder ◽  
Defect Formation ◽  
Void Formation ◽  
Experimental Results ◽  
Solder Paste ◽  
Content Type ◽  
Weight Percentage ◽  
Copper Particles ◽  
Solder Pastes

Purpose This paper aimed to investigate the effects of nano-copper particles on the melting behaviors, wettability and defect formation mechanism of the Sn58Bi composite solder pastes. Design/methodology/approach In this paper, the mechanical stirring method was used to get the nano-composite solder pastes. Findings Experimental results indicated that the addition of 3 wt.% (weight percentage) 50 nm copper particles showed limited effects on the melting behaviors of the Sn58Bi composite solder paste. The spreading rate of the Sn58Bi composite solder paste showed a decreasing trend with the increase of the weight percentage of 50 nm copper particles from 0 to 3 wt.%. With the addition of copper particles of diameters 50 nm, 500 nm or 6.5 μm into the Sn58Bi solder paste, the porosities of the three types of solder pastes showed a similar trend. The porosity increased with the increase of the weight percentage of copper particles. Based on the experimental results, a model of the void formation mechanism was proposed. During reflow, the copper particles reacted with Sn in the matrix and formed intermetallic compounds, which gathered around the voids produced by the volatilization of flux. The exclusion of the voids was suppressed and eventually led to the formation of defects. Originality/value This study provides an optimized material for the second and third level packaging. A model of the void formation mechanism was proposed.

An Alternative Model for the Kinetics of Light-Induced Defects in A-Si:H

1991 ◽  
Vol 219 ◽  
Author(s):  
Paulo V. Santos ◽  
W. B. Jackson ◽  
R. A. Street
Keyword(s):  
Time Dependence ◽  
Valence Band ◽  
Defect Formation ◽  
Defect Density ◽  
Generation Rate ◽  
Band Tail ◽  
Defect Generation ◽  
Wide Range ◽  
Induced Defects ◽  
Kinetics Of

ABSTRACTThe kinetics of light-induced defect generation in a-Si:H was investigated over a wide range of illumination intensities and temperatures. The defect density around 1016cm-3 exhibits a power-law time dependence Ns ∼ G2εfε with ε = 0.2 to 0.3, where G is the photo-carrier generation rate. A model for the kinetics of defect generation is proposed based on the existence of an exponential distribution of defect formation energies in the amorphous network, associated with the valence band tail states. The model reproduces the observed time dependence of the defect density with an exponent e determined by the exponential width of the valence band tail. The temperature dependence of the defect generation rate is well-reproduced by the model, which provides a connection between the Stabler-Wronski effect and the weak-bond model.

Formation of Defects in MBE Re-Grown GaAs Films on GaAs/AlGaAs Heterostructures

2002 ◽  
Vol 744 ◽  
Author(s):  
M. Lamberti ◽  
V. Tokranov ◽  
R. Moore ◽  
M. Yakimov ◽  
A. Katsnelson ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Defect Formation ◽  
Defect Density ◽  
Ion Beam ◽  
Stacking Faults ◽  
Tem Analysis ◽  
Planar Defects ◽  
Site Specific ◽  
Al Content ◽  
Gaas Films

ABSTRACTIn the present work, we examine the formation of defects on the sidewall slope in 1 μm - thick GaAs layers regrown on GaAs/AlGaAs heterostructures. Site-specific TEM specimens of sidewall slopes are obtained using focused ion beam combined with lift-out method. TEM analysis shows planar defects, such as stacking faults and microtwins, dislocations and large twinned areas, nucleating on the AlGaAs surfaces. SIMS and EDX reveal an increase in carbon and oxygen at the interface. The defect density increased with Al content exceeding 1010 cm-2 on Al0.4Ga0.6As. The defect formation is related to the oxidation of Al-containing surfaces.

Planar defect formation mechanism in Ge-rich SiGe-on-insulator substrates during Ge condensation process

2008 ◽  
Vol 517 (1) ◽  
pp. 407-411 ◽  
Author(s):  
Norio Hirashita ◽  
Shu Nakaharai ◽  
Yoshihiko Moriyama ◽  
Koji Usuda ◽  
Tsutomu Tezuka ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Defect Formation ◽  
Planar Defect ◽  
Condensation Process
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