Cu gettering to nanovoids in SOI materials

In this paper, the gettering of Cu impurities in silicon-on-insulator (SOI) materials is studied. Nanovoids are formed in the substrate of SOI beneath the buried oxide (BOX) by room temperature H+ (3.51016 /cm2 ) or He+ (91016 /cm2 ) implantation and subsequent annealing at 700oC. The gettering of different doses of Cu (51013/cm2, 51014 /cm2, 51015/cm2), which are introduced in the top Si layer by ion implantation, to the nanovoids are investigated by cross-section transmission electron microscopy (XTEM) and secondary ion mass spectroscopy (SIMS). The results demonstrate that Cu impurities in the top Si layer can diffuse through the bur-ied oxide (BOX) layer of SIMOX and Smart-Cut SOI at temperature above 700oC and be trapped by the nanovoids. Some of Cu impurities can be captured by the intrinsic defects at the BOX inter-face of SIMOX, but will be released out at high temperatures. The gettering effect of SIMOX intrin-sic defects at BOX is much lower than that of the nanovoids. No Cu impurities are trapped at the perfect BOX interfaces of Smart-Cut SOI. After 1000℃ annealing, high dose of Cu (3.61015 /cm2) was gettered by the nanovoids. The Cu gettering efficiency to the nanovoids increased with the decreasing of Cu doses. When the Cu doses in the top Si layer were lower than 41015 /cm2, the nanovoids could getter more than 90% of the Cu impurities and reduce the Cu concentration in the top Si layer to less than 4%. The results indicate that nanovoids gettering is a promising method for removing the impurities in SOI materials.

Hydrogen-induced cracking by nanovoids in 310 stainless steel

Hydrogen-induced cracking was investigated by TEM in-situ tension in hydrogenated stainless steel of type 310. It was found experimentally that hydrogen-induced cracking happens via nanovoid nucleation followed by quasi-cleavage along {111} planes when C H is higher. Otherwise, in the case of lower C H, hydrogen enhances ductile fracture via hydrogen-enhanced microvoid nucleation, growth and connection. A new model was proposed based on the present experiments. Dislocations break away from defect atmospheres and move away from the DFZ, leaving vacancy and hydrogen clusters along {111} planes. Hydrogen tends to combine with vacancy clusters and initiate nanovoids along {111} planes. Dense nanovoids connect each other, resulting in brittle cracking. Scattered nanovoids grow into microvoids or even macrovoids, leading to ductile fracture.

Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries

Here,we report the synthesis of hard carbon materials(RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion batteries.The studies show that the electrochemical properties of RHs are affected by the treatment temperatures,which determine the materials morphology,in particular,their degree of graphitization and extent of continuous channels(nanovoids).The latter are accessible to sodium ions and significantly contribute to charge storage capacity of the produced anodes.The RHs obtained at 1600 °C deliver the highest reversible capacity of276 mAh g^(-1) mainly due to insertion of sodium ions into the nanovoids.This work deepens the basic understanding of the influence of the carbonization temperature on the sodium storage mechanism.

Effect of void size and Mg contents on plastic deformation behaviors of Al-Mg alloy with pre-existing void:Molecular dynamics study

The plastic deformation properties of cylindrical pre-void aluminum-magnesium(Al-Mg)alloy under uniaxial tension are explored using molecular dynamics simulations with embedded atom method(EAM)potential.The factors of Mg content,void size,and temperature are considered.The results show that the void fraction decreases with increasing Mg in the plastic deformation,and it is almost independent of Mg content when Mg is beyond 5%.Both Mg contents and stacking faults around the void affect the void growth.These phenomena are explained by the dislocation density of the sample and stacking faults distribution around the void.The variation trends of yield stress caused by void size are in good agreement with the Lubarda model.Moreover,temperature effects are explored,the yield stress and Young’s modulus obviously decrease with temperature.Our results may enrich and facilitate the understanding of the plastic mechanism of Al-Mg with defects or other alloys.