نتایج جستجو برای: aln
تعداد نتایج: 3323 فیلتر نتایج به سال:
Infrared reflection spectroscopy is applied to state-of-the-art thin film heterostructures of group-III nitrides on sapphire and Si substrates. The individual layers of GaN and AlGaN and the AlN buffer layer are identified by their phonon frequencies. Under non-perpendicular incidence of the light, A1~LO! phonon modes are observed in the wurtzite system. The presence of the very thin AlN buffer...
Bulk aluminium nitride (AlN) is a very promising substrate material for UV optoelectronics based on AlGaN ternary compounds. AlN single crystals exceeding 1'' in diameter can now be grown by physical vapour transport (PVT). UV transparency is of high interest for UV devices designed to emit through the substrate. We report on 500 μm thick bulk AlN substrates with plain UV transmittance of 50% (...
Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amo...
در این پژوهش ویسکرهای نیترید آلومینیوم (aln) در کوره لوله ای تحت جریان 500 گاز نیتروژن در دمای c˚1000 با یک ساعت ماندگاری در این دما تهیه شدند. مواد اولیه شامل آلومینیوم (al) با اندازه ذرات 3 میکرومتر و 45 میکرومتر و کلرید آمونیوم (nh4cl) بود. برای بررسی ویسکرهای نیترید آلومینیوم، میکروسکوپ الکترونی روبشی (sem)، میکروسکوپ الکترونی عبوری (tem) و پراش اشعه x (xrd) به کار گرفته شدند. بررسی یافته ه...
A planar force-constant model is developed for longitudinal phonons of wurtzite GaN and AlN propagating along the [0001] direction. The proposed model is then applied to the study of the phonon modes in hexagonal (0001)GaN/AlN supperlattices in longitudinal polarization. The confinement of the superlattice phonon modes is discussed. PACS numbers: 68.20.Dj, 68.35.Ja Typeset using REVTEX
In this study, a combustion synthesized AlN powder was sintered using microwave as heating source. The microwave was 2.45 GHz and the sintering process was carried out in a single-mode cavity. The sintering temperature was between 1800°C and 2000°C with a power ranging from 400 to 700W. The as-synthesized AlN was ground to under 2μm and yttria was used as sintering aid. The effects of the amoun...
Axillary lymph node (ALN) status is currently used as an important clinical indicator of breast cancer prognosis. However, the molecular mechanisms underlying lymph node metastasis are poorly understood and the relationship between ALN metastasis and the primary tumor remains unclear. In an effort to reveal structural changes in the genome and related protein responses that may drive regional m...
Current Internet hosts open new connections that are initialized with a number of default, generally conservative, parameters. Applied Learning Networks (ALN) apply accumulated experience with previous network connections to help tune initial parameters for future network connections. ALN provides a demonstration of nontrivial learning in complex communication protocols such as TCP that result ...
در این پژوهش خواص الکترونی و اپتیکی نانو ساختارهای تک لایه aln و gaas براساس اصول اولیه تابع گرین بس- ذره ای و فرمول بندی معادله بته- سالپیتر محاسبه شده است. تصحیحات انرژی به ویژه مقادیر dft با استفاده از تقریب gw برای مواد انجام شدند، تا اینکه مقدار گاف های انرژی بدست آیند. با استفاده از تصحیحات شبه- ذره گاف انرژی غیرمستقیم تک لایه لانه زنبوری aln 8/5 الکترون ولت (gaas 42/3 الکترون ولت) محاسبه...
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