Characteristic improvements of thin film AlGaInP red light emitting diodes on a metallic substrate

We report a type of thin film Al Ga In P red light emitting diode(RLED) on a metallic substrate by electroplating copper(Cu) to eliminate the absorption of Ga As grown substrate.The fabrication of the thin film RLED is presented in detail.Almost no degradations of epilayers properties are observed after this substrate transferred process.Photoluminescence and electroluminescence are measured to investigate the luminous characteristics.The thin film RLED shows a significant enhancement of light output power(LOP) by improving the injection efficiency and light extraction efficiency compared with the reference RLED on the Ga As parent substrate.The LOPs are specifically enhanced by 73.5% and 142% at typical injections of 2 A/cm~2 and 35 A/cm~2 respectively from electroluminescence.Moreover,reduced forward voltages,stable peak wavelengths and full widths at half maximum are obtained with the injected current increasing.These characteristic improvements are due to the Cu substrate with great current spreading and the back reflection by bottom electrodes.The substrate transferred technology based on electroplating provides an optional way to prepare high-performance optoelectronic devices,especially for thin film types.     

Effect of FeS doping on large diamond synthesis in FeNi-C system

The large single-crystal diamond with FeS doping along the(111) face is synthesized from the FeNi–C system by the temperature gradient method(TGM) under high-pressure and high-temperature(HPHT). The effects of different FeS additive content on the shape, color, and quality of diamond are investigated. It is found that the(111) face of diamond is dominated and the(100) face of diamond disappears gradually with the increase of the FeS content. At the same time, the color of the diamond crystal changes from light yellow to gray-green and even gray-yellow. The stripes and pits corrosion on the diamond surface are observed to turn worse. The effects of FeS doping on the shape and surface morphology of diamond crystal are explained by the number of hang bonds in different surfaces of diamond. It can be shown from the test results of the Fourier transform infrared(FTIR) spectrum that there exists an S element in the obtained diamond. The N element content values in different additive amounts of diamond are calculated. The XPS spectrum results demonstrate that our obtained diamond contains S elements that exist in S–C and S–C–O forms in a diamond lattice. This work contributes to the further understanding and research of FeS-doped large single-crystal diamond characterization.     

极紫外光源及高荷态离子诱导下甲烷的脱氢通道碎裂机制

CH₄广泛存在于行星大气之中,研究CH₄的解离动力学对了解宇宙中气体演化的过程具有重要的价值.目前,CH₄²⁺ →CH₃⁺+H⁺碎裂通道已被大量研究,但针对该通道的解离机制的解释尚存在一定争议.本实验利用高分辨反应显微成像谱仪,开展了25—44 eV的极紫外(extreme ultraviolet, XUV)光电离实验及1 MeV Ne⁸⁺与CH₄的碰撞实验.通过符合测量得到了CH₃⁺和H⁺两种离子的动能,重构了两体解离的动能释放(kinetic energy release, KER),并研究了CH₄²⁺解离产生CH₃⁺+H⁺解离路径下的碎裂动力学过程.在光电离实验中,观测到KER谱上存在4.75 eV和6.09 e...     

新型城镇化下的浙江省城际竞争力差异比较

对浙江省城际竞争力差异进行比较, 同时尽可能准确反映出每个城市的综合实力, 以浙江省最新社会经济统计数据为基础, 采用主成分分析和综合分析方法对具有代表性的35个指标数据进行处理分析. 最后得出第一梯队城市只有杭州市, 第二梯队城市有宁波、温州、嘉兴3个城市, 其余7个城市在第三梯队. 由此可知, 浙江省城际之间呈金字塔型分布, 塔尖城市数量少, 中坚力量薄弱, 塔底城市数量大, 同时城际间差距较大, 城市内部经济结构有待进一步优化.     

浙江信息服务业发展格局及其影响因素

信息服务业是伴随信息技术广泛应用逐渐兴起的新兴产业, 成为当今中国产业创新发展的重要方向. 文中系统阐释了信息服务业范畴, 厘清了信息服务业的经济地理学研究内容与方法体系. 运用主成分、多元回归、空间相关分析等方法分析浙江省2004年、2008年经济普查数据, 探究浙江信息服务业重点行业空间分布及其影响因素. 研究发现: (1)全省信息服务业重点行业空间分布格局趋于分散; 市域层面沿海及中部地区集聚水平高; 浙北、浙西南以及舟山的集聚水平较低. (2) 影响信息服务业发展因素中,人才、技术、政府支持等最为重要.     

Synthesis of N-type semiconductor diamonds with sulfur,boron co-doping in FeNiMnCo-C system at high pressure and high temperature

A series of diamonds with boron and sulfur co-doping were synthesized in the Fe Ni Mn Co-C system by temperature gradient growth(TGG) under high pressure and high temperature(HPHT). Because of differences in additives, the resulting diamond crystals were colorless, blue-black, or yellow. Their morphologies were slab, tower, or minaret-like. Analysis of the x-ray photoelectron spectra(XPS) of these diamonds shows the presence of B, S, and N in samples from which N was not eliminated. But only the B dopant was assuredly incorporated in the samples from which N was eliminated. Resistivity and Hall mobility were 8.510 ?·cm and 760.870 cm~2/V·s, respectively, for a P-type diamond sample from which nitrogen was eliminated. Correspondingly, resistivity and Hall mobility were 4.211×10~5 ?·cm and 76.300 cm~2/V·s for an N-type diamond sample from which nitrogen was not eliminated. Large N-type diamonds of type Ib with B–S doping were acquired.     

Boundary normal pressure-based electrical conductivity reconstruction for magneto–acoustic tomography with magnetic induction

As a kind of multi-physics imaging approach integrating the advantages of electrical impedance tomography and ultrasound imaging with the improved spatial resolution and image contrast, magneto–acoustic tomography with magnetic induction(MAT-MI) is demonstrated to have the capability of electrical impedance contrast imaging for biological tissues with conductivity differences. By being detected with a strong directional transducer, abrupt pressure change is proved to be generated by the gradient of the induced Lorentz force along the force direction at conductivity boundary. A simplified boundary normal pressure(BNP)-based conductivity reconstruction algorithm is proposed and the formula for conductivity distribution inside the object with the clear physical meaning of pressure derivative, is derived. Numerical simulations of acoustic pressure and conductivity reconstruction are conducted based on a 2-layer eccentric cylindrical phantom model using Hilbert transform. The reconstructed two-dimensional conductivity images accord well with the model, thus successfully making up the deficiency of only imaging conductivity boundary in traditional MAT-MI. The proposed method is also demonstrated to have a spatial resolution of one wavelength. This study provides a new method of reconstructing accurate electrical conductivity and suggests the potential applications of MAT-MI in imaging biological tissues with conductivity difference.     

Sr3Lu(PO4)3:Pr3+荧光材料的制备与光致发光研究

采用高温固相法成功合成了Sr3Lu(PO4)3:Pr3+荧光粉.通过X射线衍射、扫描电子显微镜和光谱技术,分别研究了Sr3Lu(PO4)3:Pr3+荧光粉的晶体结构,表面形貌和光致发光谱.研究结果表明:所合成Sr3Lu(PO4)3:Pr3+荧光粉具有立方的I43d空间对称结构,其表面具有不规则的颗粒形貌,光致激发波长为444nm,发射波长为610nm,所发光为红色光,当掺杂浓度为1;的时发光效果最好.     

薄层稠油藏溶剂辅助蒸汽驱产量预测模型

通过分析生产数据和数值模拟结果,将薄层稠油油藏溶剂辅助蒸汽驱生产过程分为蒸汽前缘垂向扩展阶段、蒸汽前缘水平扩展阶段及冷凝水产出阶段.针对每个生产阶段,通过联合质量守恒方程、运动方程、能量守恒方程及溶剂扩散方程得到描述蒸汽前缘扩展和产油量解析模型.能量守恒方程属于典型的第二类Volterra 积分函数,首先对其进行Laplace变换;之后运用半解析方法对该模型进行求解.为验证模型的正确性,将模型的溶剂辅助蒸汽驱计算结果与数值模拟结果对比,整体误差仅为4%.新模型可以方便简单地分析不同溶剂性能和注采参数对溶剂蒸汽驱开发效果的影响.     

基于卡车加载和差分曲率的简支梁桥预警新指标

差分曲率指标在实际用于损伤识别时受到加载方式的限制.为此,首先采用了一种卡车加载方式,通过两次卡车加载可实现集中载荷的工况,并对简支梁桥建立起了相应的损伤识别方法,提出了新的"卡车载荷差分曲率指标(truck load difference curvature indicator,TLDCI)".基于实测的竖向位移数据得到的TLDCI图形可识别损伤的出现和位置信息,从而实现简支梁桥的状态预警.TLDCI方法的计算简单而且不需要与结构完好状态下的数据进行对比.所提出方法的有效性通过算例得到了证明,并最后讨论了提高其稳定性的措施.