752 resultados para 111 Mathematics


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用电子束蒸发方法在Si(111)衬底上蒸发了Au/Cr和Au/Ti/Al/Ti两种金属缓冲层,然后在金属缓冲层上用气源分子束外延(GSMBE)生长GaN.两种缓冲层的表面都比较平整和均匀,都是具有Au(111)面择优取向的立方相Au层.在Au/Cr/Si(111)上MBE生长的GaN,生长结束后出现剥离.在Au/Ti/Al/Ti/Si(111)上无AlN缓冲层直接生长GaN,得到的是多晶GaN;先在800℃生长一层AlN缓冲层,然后在710℃生长GaN,得到的是沿GaN(0001)面择优取向的六方相GaN.将Au/Ti/Al/Ti/Si(111)在800℃下退火20min,金属层收缩为网状结构,并且成为多晶,不再具有Au(111)方向择优取向.

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在硅衬底上利用具有质量选择功能的低能离子束沉积技术沉积碳离子制备出除碳、硅之外无其他杂质元素的纯净的立方SiC薄膜.利用X射线光电子谱、俄歇电子能谱、X射线衍射对样品进行了表征.结果显示常温和400℃制备的样品为非晶结构,在800℃制备的样品由一富碳的表面层和有着良好化学计量比的SiC层组成,碳化硅晶体薄膜是(111)织构的.通过分析可知衬底温度、离子沉积能量和样品保温扩散时间等因素综合在一起对于在硅上沉积SiC薄膜起着重要作用.远远大于TRIM预测厚度的SiC薄膜的获得是高的衬底温度、一定注入能量的碳离子引起的增强扩散以及通道注入效应综合作用的结果。

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50mm SiC films with high electrical uniformity are grown on Si(111) by a newly developed vertical low-pressure chemical vapor deposition (LPCVD) reactor.Both in-situ n- and p-type doping of 3C-SiC are achieved by intentional introduction of ammonia and boron into the precursor gases.The dependence of growth rate and surface morphology on the C/Si ratio and optimized growth conditions is obtained.The best electrical uniformity of 50mm 3C-SiC films obtained by non-contact sheet resistance measurement is ±2.58%.GaN films are grown atop the as-grown 3C-SiC/Si(111) layers using molecular beam epitaxy (MBE).The data of both X-ray diffraction and low temperature photoluminescence of GaN/3C-SiC/Si(111) show that 3C-SiC is an appropriate substrate or buffer layer for the growth of Ⅲ-nitrides on Si substrates with no cracks.

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为了研究(111)衬底的特性以及实现等边三角形微腔激光器,利用金属有机化学气相淀积(MOCVD)研究了(111)A InP衬底上InGaAsP外延层的表面形貌和光学特性。考虑到(111)A InP衬底的悬挂键密度比较低,在生长过程中有意提高了V/III比。通过扫描电子显微镜(SEM)和光荧光(PL)谱分别研究了外延层的表面形貌和光学特性。实验发现,表面形貌和光学特性随V/III比和温度的变化非常大。最佳V/IlI比和温度分别为400和625℃。

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采用AlN插入层技术在Si(111)衬底上实现无微裂GaN MOCVD生长.通过对GaN外延层的a,c轴晶格常数的测量,得到了GaN所受张应力与AlN插入层厚度的变化关系.当AlN厚度在7~13nm范围内,GaN所受张应力最小,甚至变为压应力.因此,GaN微裂得以消除.同时研究了AlN插入层对GaN晶体质量的影响,结果表明,许多性能相比于没有AlN插入层的GaN样品有明显提高.

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利用衍衬、SAED、HRTEM对在(111)Si上外延生长的六方GaN进行了观察分析。GaN外延层与缓冲层和基底的取向关系为(0001)_(GaN)∥(0001)_(AlN)∥(111)_(Si),[11(2-bar)0]_(GaN)∥[11(2-bar)0]_(AlN)∥[110]_(Si)。GaN外延层中存在倒反畴。GaN中位错以刃型位错为主。In_(0.1) Ga_(0.9) N/GaN的多重量子阱结构(MQW)具有阻挡穿透位错,降低位错密度的作用。

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国家973计划

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于2010-11-23批量导入

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于2010-11-23批量导入

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采用质量分离的低能双离子束淀积(IBD)技术,在硅(111)衬底上共淀积,生长了氧化铈外延薄膜。椭圆偏振仪测得,膜厚2000A。俄歇能谱仪测得,外延层内铈、氧分布均匀,具有很好的正化学比。X射线双晶衍射得到明显的氧化铈(111),(222)峰,半高宽≤23''。

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Polycrystalline GaN thin films have been deposited epitaxially on a ZnO-buffered (111)-oriented Si substrate by molecular beam epitaxy. The microstructural and compositional characteristics of the films were studied by analytical transmission electron microscopy (TEM). A SiO2 amorphous layer about 3.5 nm in thickness between the Si/ZnO interface has been identified by means of spatially resolved electron energy loss spectroscopy. Cross-sectional and plan-view TEM investigations reveal (GaN/ZnO/SiO2/Si) layers exhibiting definite a crystallographic relationship: [111](Si)//[111](ZnO)//[0001](GaN) along the epitaxy direction. GaN films are polycrystalline with nanoscale grains (similar to100 nm in size) grown along [0001] direction with about 20degrees between the (1 (1) over bar 00) planes of adjacent grains. A three-dimensional growth mode for the buffer layer and the film is proposed to explain the formation of the as-grown polycrystalline GaN films and the functionality of the buffer layer. (C) 2004 Elsevier Ltd. All rights reserved.

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The growth of wurtzite GaN by low-pressure metalorganic vapor-phase epitaxy on (1 1 1) magnesium aluminate (MgAl2O4) substrates have been studied. The morphological, crystalline, electrical and optical properties are investigated. A p-n junction GaN LED was fabricated on the MgAl2O4 substrate. (C) 1998 Elsevier Science B.V. All rights reserved.

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A polycrystalline silicon thin film was fabricated on glass substrate by means of aluminum induced crystallization (AIC). Al and alpha-Si layers were deposited by magnetron sputtering respectively and annealed at 480A degrees C for 1 h to realize layer exchange. The polycrystalline silicon thin film was continuous and strongly (111) oriented. By analyzing the structure variation of the oxidation membrane and lattice mismatch between gamma-Al2O3 and Si, it was concluded that aluminum promoted the formation of (111) oriented silicon nucleus by controlling the orientation of gamma-Al2O3, which was formed at the early stage of annealing.