نتایج جستجو برای: vapour phase
تعداد نتایج: 606226 فیلتر نتایج به سال:
polycyclic aromatic hydrocarbons (pahs) are toxic pollutants released by various urban combustion sources. tehran is the largest city in iran with a population of about 8 million and it is faced with serious air quality problems. the gas phase samples collected from 21 sites in tehran area throughout year 2005. the samples‘ pahs were collected using a skc trapping consisting of glass cartridg...
from SciFinder
In this article two methods for improvements of (112̄2) oriented semipolar GaN grown by MOVPE on pre-structured sapphire substrates are investigated. The integration of a SiNx interlayer helps to obtain a better crystal quality. Also the overgrowth of the MOVPE samples by HVPE is a way to obtain a smoother GaN surface. A high incorporation of oxygen on (112̄2) oriented GaN compared to (0001) orie...
Thick GaN layers have been grown by hydride vapor phase epitaxy (HVPE) on different GaN templates grown by metalorganic vapor phase epitaxy. Crack formation could be reduced by using a hydrogen/nitrogen carrier gas mixture. By carefully optimizing the growth conditions in the final stage of the process, excellent surface morphologies could be obtained at still acceptably high growth rates. Up t...
There is some experimental evidence that some stars are older than the Universe in General Relativity based cosmology. In TGD based cosmology the paradox has explanation. Photons can be either topologically condensed on background spacetime surface or in ’vapour phase’ that is progate in M + × CP2 as small surfaces. The time for propagation from A to B is in general larger in condensate than in...
A major challenge that arises when growing GaN substrates in a single run process is the remaining curvature of the freestanding material after the removal of the foreign substrate. For a long time the dislocation density gradient has been suspected to be the cause. However, by conducting etching experiments, we have found that this cannot be the only reason. We postulate that the initial strai...
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