SiC薄膜的制备和发光特性的研究

目的 制备SiC薄膜并对其发光特性进行研究. 方法 用射频溅射法在玻璃衬底上制备SiC薄膜,退火处理后并利用光致发光谱(PL)对发光性能进行分析. 结果 SiC薄膜样品在紫外区存在360 nm和370 nm两个发光峰,峰的强度都随着腐蚀时间的增长而增加,在t=20 min时达到最大,然后强度减小,而且峰的强度随退火温度升高而增加,在蓝光区存在470 nm发光峰,峰的强度随退火温度升高而增加. 结论 玻璃衬底腐蚀时间为20 min,SiC沉积时间为1 h时样品表现出了比较好的发光特性,在紫外区和蓝光区出现了光致发光,样品的发光强度随退火温度的增加显著增强.     

非晶态Ni—Si—B系合金结构驰豫的电阻法研究

本文通过精密测定非晶态Ｎｉ－Ｓｉ－Ｂ系合金的电阻率在不同温度下等时退火后的变化，研究了该合金的结构驰豫过程，得到其电阻率变化随退火温度而作振荡性起伏的关系曲线，并利用作者提出的结构缺陷形成机制对该振荡性曲线作出了比较合理的微观机理解释。     

退火对掺铟氧化锌薄膜结构及光学性能的影响

采用溶胶-凝胶法在石英衬底上制备掺铟氧化锌薄膜,研究不同退火温度对薄膜结构及发光性能的影响.结果表明,掺铟氧化锌薄膜仍为六角纤锌矿结构的ZnO相,在大于450 nm的波段薄膜样品的透射率都较高;随着退火温度的升高,透射率先增后减,600℃时达到最大;薄膜样品的光学带隙都小于纯ZnO的理论值(3.37 eV),且随退火温度的升高呈先减后增趋势;样品的结晶度与发光强度随着退火温度的升高而增强.     

退火对Ni74Si10B16非晶合金电阻温度特性的影响

采用DC四端电阻测试法，测试了不同退火条件下Ni74Sil0B16非晶合金223～423K温区的电阻温度特性曲线，发现：淬态与退火态非晶合金试样的电阻均随温度近线性变化，并且，随着退火时间的延长或退火温度的升高，非晶合金电阻温度系数α上升，而室温电阻率ρ0下降，基于Nagel推广的液态金属Ziman理论，本文对此结果进行了分析和讨论。     

热重与差示扫描量热分析法联用研究钙、镁、锌配合物的热性质

为了得到金属配合物的热性质,对化学反应法研究制备的氨基酸镁、钙、锌金属配合物(C_(10)H_20NCO_3-)进行了差示扫描量热(DSC)和热重差热(TGA-DTA)联用分析,得到了3种金属配合物的TGA-DTA和DSC曲线,并获取其金属配合物的非晶态的玻璃化转变温度、结晶态的融解焓、吸热以及失重质量等。另外,对配合物进行了元素分析,金相显微镜分析等表征。研究表明,氨基酸钙配合物容易形成非晶态(玻璃态);氨基酸镁配合物容易形成晶态与非晶态的混合态,经过加热冷却处理后可以形成玻璃态;氨基酸锌配合物容易形成结晶态。     

纳米铜薄膜瞬态热输运过程试验研究与数值模拟分析

利用磁控溅射法制备厚度100 nm的铜薄膜,使用800 nm泵浦和400 nm探测瞬态反射技术,测量铜薄膜的时间分辨反射率,分析铜薄膜在飞秒激光作用下瞬态热输运过程。利用双温模型对铜薄膜热输运过程进行数值模拟,模拟结果显示电子和晶格体系温度变化过程,电声耦合系数为1.2×1016W·m-3K。变换参数进行模拟,分析薄膜厚度和电声耦合系数对非平衡热输运过程影响规律,为铜薄膜在集成电路中应用提供参考。     

硫化温度和时间对SnxSy薄膜结构和成分的影响

用热蒸发技术在玻璃基片上沉积一层sn薄膜,在真空条件下,将其在150～300℃下硫化30．60min．对在不同温度和时间下硫化的薄膜进行结构、成分和表面形貌分析,结果表明：在不同温度和不同时间下硫化,所得到的薄膜在物相结构、成分和表面形貌上都存在差异．当硫化温度为240℃、硫化时间为45min时,所制得的薄膜为正交结构的SnS多晶薄膜,其均匀性、致密性以及对基片的附着力都较好,具有（111）方向优先生长,薄膜粒径在200～800nm,且晶格常数与标样的数值吻合很好．     

化学镀Fe—Mo—W—B合金镀层的磁损耗

利用化学镀的方法制备了非晶态Ｆｅ－Ｍｏ－Ｗ－Ｂ四元合金镀层，利用Ｘ射线衍射方法屯镀层的结构，样品的磁损耗的由交流互感电桥原理测量，结果表明：具有较宽形成玻璃体能力的成分区域同时具有较低的磁损耗，与Ｆｅ－Ｍｏ－Ｂ非晶态合金镀层比较，Ｗ元素的加入并不明显改善镀层磁损耗，同时研究了样品在逐步退火过程中磁损耗随退火温度的变化规律。     

溅射制备的Al2O3薄膜的光学性质

采用中频反应磁控溅射技术,在石英基片上制备了氧化铝薄膜.研究了氧化铝薄膜的XRD谱和Al 2p核心能级的XPS谱随不同制备氧分压比的演变规律.结果表明:随着制备氧分压比的增加,薄膜中的铝元素从金属态逐渐升高到正3价,同时薄膜由晶态逐渐转变成非晶态.当氧分压比为11%时,可以得到符合化学计量比的、非晶态的、表面非常光滑的氧化铝薄膜,该薄膜具有较高的折射率和较低的消光系数.AFM表面相貌图片显示:随氧分压比增加薄膜表面形貌呈现逐渐光滑的趋势.薄膜在300～1100nm波段有很高的透射率.以上性质表明用中频反应磁控溅射技术制备的氧化铝薄膜在光学领域有着广泛的应用前景.     

快速退火炉离子注入退火工艺设计

研究了快速热处理系统中卤钨灯阵列的排列方式和硅片接受到的辐照度均匀性的关系,设计了一种可以满足硅片温度均匀性要求的轴对称排列的灯阵列形式.卤钨灯分布在三个半径分别为5,10,16.8 cm的同心圆上,线密度分别为0.127,0.191,0.341cm-1,加热头高度为10.2 cm.此时辐照度的标准差有最小值,保证了硅片边缘和硅片中心能够得到尽可能一致的辐照.接着进行了P离子注入快速热退火试验,测量比较了退火后样品的方块电阻值,获得了快速热退火的最佳温度时间关系参数.对于剂量7.0×1015cm-2,能量60 keV的P离子注入,快速热退火的最佳温度为1000°C,稳定10 s.     

Controlling molecular order in "hairy-rod" langmuir-blodgett films: a polarization-modulation microscopy study

The interplay of molecular weight, layer thickness, and thermal annealing in controlling molecular order in ultrathin Langmuir-Blodgett films is characterized with the use of polarization-modulation laser-scanning microscopy. The degree and direction of molecular alignment can be imaged rapidly and sensitively through the magnitude and orientation of linear dichroism in Langmuir-Blodgett films of rodlike poly(phthalocyaninatosiloxane) (PcPS). Images are presented for films as thin as two molecular layers ( approximately 44 angstroms). Molecular alignment along the transfer direction is much stronger for films of PcPS with approximately 25 repeat units ( approximately 10 nanometers long) than for those with approximately 50 repeat units ( approximately 20 nanometers long). Enhancement of alignment by thermal annealing is also much greater for PcPS-25 than PcPS-50. Intimate interaction with the substrate suppresses improvement in alignment by annealing, evident by an anomalously small increase in anisotropic absorption of the first two layers.     

Nanometer-thick equilibrium films: the interface between thermodynamics and atomistics

Nanometer-thick films at interfaces and surfaces exist in various materials and can substantially influence their properties. Whether these films are an equilibrium or transient state is debated. To address this question, we equilibrated 1.2-nanometer-thick films at gold-sapphire interfaces in the presence of anorthite glass and measured the solid-solid interface energy. The equilibrated film significantly reduced the interfacial energy and could be described by the Gibbs adsorption isotherm expanded to include structure in addition to chemical excess. Unlike artificially made conventional thin films, these films do not break up during equilibration and offer an alternative design criterion for thin-film technology. These results demonstrate that nanometer-thick films at interfaces and surfaces can be an equilibrium state and included in phase diagrams with dedicated tie-lines.     

Single-Crystal Epitaxial Thin Films of the Isotropic Metallic Oxides Sr1-xCaxRuO3 (0 le x le 1)

Single-crystal epitaxial thin films of the isotropic metallic oxides Sr1-xCaxRuO(3) (0 相似文献   

金属热防护系统多层隔热材料的传热分析及参数优化

采用能量平衡方程和离散坐标法近似地建立了金属热防护系统多层隔热材料的一维稳态传热的数学模型，并利用遗传算法和纤维隔热材料的有效导热系数试验数据求解传热反问题，从而得到了模型中的纤维隔热材料的辐射衰减系数、反照率和隔热屏表面辐射发射系数。最后，由实验测得了多层隔热材料的有效导热系数，验证了采用优化参数后，多层隔热材料的传热模型的正确性。     

Theory of quantum annealing of an Ising spin glass

Probing the lowest energy configuration of a complex system by quantum annealing was recently found to be more effective than its classical, thermal counterpart. By comparing classical and quantum Monte Carlo annealing protocols on the two-dimensional random Ising model (a prototype spin glass), we confirm the superiority of quantum annealing relative to classical annealing. We also propose a theory of quantum annealing based on a cascade of Landau-Zener tunneling events. For both classical and quantum annealing, the residual energy after annealing is inversely proportional to a power of the logarithm of the annealing time, but the quantum case has a larger power that makes it faster.     

Electrical Transport Properties of Undoped CVD Diamond Films

Polycrystalline diamond films synthesized by microwave-assisted chemical vapor deposition (MACVD) were examined with transient photoconductivity, and two fundamental electrical transport properties, the carrier mobility and lifetime, were measured. The highest mobility measured is 50 centimeters squared per volt per second at low initial carrier densities (<10(15) per cubic centimeter). Electron-hole scattering causes the carrier mobility to decrease at higher carrier densities. Although not measured directly, the carrier lifetime was inferred to be 40 picoseconds. The average drift length of the carriers is smaller than the average grain size and appears to be limited by defects within the grains. The carrier mobility in the MACVD films is higher than values measured in lower quality dc-plasma films but is much smaller than that of single-crystal natural diamond.     

Local Control of Microdomain Orientation in Diblock Copolymer Thin Films with Electric Fields

Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication.     

Bolometric infrared photoresponse of suspended single-walled carbon nanotube films

The photoresponse in the electrical conductivity of a single-walled carbon nanotube (SWNT) film is dramatically enhanced when the nanotube film is suspended in vacuum. We show here that the change in conductivity is bolometric (caused by heating of the SWNT network). Electron-phonon interactions lead to ultrafast relaxation of the photoexcited carriers, and the energy of the incident infrared (IR) radiation is efficiently transferred to the crystal lattice. It is not the presence of photoexcited holes and electrons, but a rise in temperature, that results in a change in resistance; thus, photoconductivity experiments cannot be used to support the band picture over the exciton model of excited states in carbon nanotubes. The photoresponse of suspended SWNT films is sufficiently high that they may function as the sensitive element of an IR bolometric detector.