939 resultados para V Foro Crítica


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Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

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Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-06-04T08:36:34Z No. of bitstreams: 1 dspace.cfg: 33388 bytes, checksum: ac9630d3fdb36a155287a049e8b34eb7 (MD5)

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Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-06-04T08:36:34Z No. of bitstreams: 1 dspace.cfg: 33388 bytes, checksum: ac9630d3fdb36a155287a049e8b34eb7 (MD5)

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Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-06-04T08:36:34Z No. of bitstreams: 1 dspace.cfg: 33388 bytes, checksum: ac9630d3fdb36a155287a049e8b34eb7 (MD5)

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一种掺Yb双包层光纤激光器v形槽侧面粘和泵浦方法,其特征在于,包括如下步骤:步骤1:在双包层光纤的内包层和外包层上用精密光学微加工技术沿双包层光纤的轴向加工一段v形槽,该v形槽的底部高于双包层光纤的纤芯的表面;步骤2:将多模尾纤的一端用化学腐蚀方法去掉涂敷层,得到裸尾纤;步骤3:将多模尾纤一端的裸尾纤放入双包层光纤的v形槽内,该裸尾纤与纤芯相隔一距离;步骤4:使用光学折射率匹配胶填充于v形槽内,使裸尾纤与纤芯平行固定于v形槽内。

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本发明提供一种采用氢氧化铵腐蚀液制备V型槽砷化镓图形衬底的方法,其特征在于,包括如下步骤:步骤1:配置氢氧化铵腐蚀液;步骤2:在衬底上制作一层光刻胶;步骤3:光刻,使光刻胶形成条形光刻胶图案;步骤4:将光刻好的衬底放入配好的腐蚀液中腐蚀,使衬底形成V型槽,取出,用去离子水反复清洗,然后氮气吹干;步骤5:将吹干后的衬底用丙酮清洗掉残留的光刻胶,氮气吹干,完成V型槽砷化镓图形衬底的制作。

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A series of metamorphic high electron mobility transistors (MMHEMTs) with different V/III flux ratios are grown on GaAs (001) substrates by molecular beam epitaxy (XIBE). The samples are analysed by using atomic force microscopy (AFM), Hall measurement, and low temperature photoluminescence (PL). The optimum V/III ratio in a range from 15 to 60 for the growth of MMHEMTs is found to be around 40. At this ratio, the root mean square (RMS) roughness of the material is only 2.02 nm; a room-temperature mobility and a sheet electron density are obtained to be 10610.0cm(2)/(V.s) and 3.26 x 10(12)cm(-2) respectively. These results are equivalent to those obtained for the same structure grown on InP substrate. There are two peaks in the PL spectrum of the structure, corresponding to two sub-energy levels of the In0.53Ga0.47 As quantum well. It is found that the photoluminescence intensities of the two peaks vary with the V/III ratio, for which the reasons are discussed.

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Using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V, and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the reference level volume deformation and offers a more reliable prediction of the "natural" unstrained offsets. Comparison is made to experimental work, where a noticeable improvement is found compared to previous methodologies.

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The effects of growth temperature and V/III ratio on the InN initial nucleation of islands on the GaN (0 0 0 1) surface were investigated. It is found that InN nuclei density increases with decreasing growth temperature between 375 and 525 degrees C. At lower growth temperatures, InN thin films take the form of small and closely packed islands with diameters of less than 100 nm, whereas at elevated temperatures the InN islands can grow larger and well separated, approaching an equilibrium hexagonal shape due to enhanced surface diffusion of adatoms. At a given growth temperature of 500 degrees C, a controllable density and size of separated InN islands can be achieved by adjusting the V/III ratio. The larger islands lead to fewer defects when they are coalesced. Comparatively, the electrical properties of the films grown under higher V/III ratio are improved.