氮化铝薄膜的低温沉积

介绍了一种 ECR微波放电和脉冲激光沉积相结合低温沉积 Al N薄膜的新方法 .在 ECR氮等离子体环境中用脉冲激光烧蚀 Al靶 ,以低于 80℃的衬底温度在 Si衬底上沉积了 Al N薄膜 .结合样品表征和等离子体光谱分析 ,探讨了膜层沉积的机理 ,等离子体中活性氮物质的存在是 Al- N化合的重要因素 ,等离子体对衬底的辐照促进膜层的形成     

液晶光子晶体可调自准直特性研究

液晶材料光子晶体由于具有可调谐性而得到了广泛的研究,但目前的研究主要集中在可调的光子带隙特性上。详细研究了液晶光子晶体的可调自准直特性。使用平面波展开法分析了液晶旋转角对光子晶体自准直频率的影响,并使用时域有限差分法对光在液晶光子晶体中的传输进行了仿真。结果表明,通过控制液晶旋转角,可以对光子晶体自准直频率进行调节,从而满足不同频率自准直的需要。     

Wireless Energy Transfer System with Multiple Coils via Coupled Magnetic Resonances

A general equivalent circuit model is developed for a wireless energy transfer system composed of multiple coils via coupled magnetic resonances. To verify the developed model, four types of wireless energy transfer systems are fabricated, measured, and compared with simulation results. To model a system composed of n‐coils, node equations are built in the form of an n‐by‐n matrix, and the equivalent circuit model is established using an electric design automation tool. Using the model, we can simulate systems with multiple coils, power sources, and loads. Moreover, coupling constants are extracted as a function of the distance between two coils, and we can predict the characteristics of a system having coils at an arbitrary location. We fabricate four types of systems with relay coils, two operating frequencies, two power sources, and the function of characteristic impedance conversion. We measure the characteristics of all systems and compare them with the simulation results. The flexibility of the developed model enables us to design and optimize a complicated system consisting of many coils.     

16‐QAM‐Based Highly Spectral‐Efficient E‐band Communication System with Bit Rate up to 10 Gbps

This paper presents a novel 16‐quadrature‐amplitude‐modulation (QAM) E‐band communication system. The system can deliver 10 Gbps through eight channels with a bandwidth of 5 GHz (71‐76 GHz/81‐86 GHz). Each channel occupies 390 MHz and delivers 1.25 Gbps using a 16‐QAM. Thus, this system can achieve a bandwidth efficiency of 3.2 bit/s/Hz. To implement the system, a driver amplifier and an RF up‐/down‐conversion mixer are implemented using a 0.1 µm gallium arsenide pseudomorphic high‐electron‐mobility transistor (GaAs pHEMT) process. A single‐IF architecture is chosen for the RF receiver. In the digital modem, 24 square root raised cosine filters and four (255, 239) Reed‐Solomon forward error correction codecs are used in parallel. The modem can compensate for a carrier‐frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10^?5 at a signal‐to‐noise ratio of about 21.5 dB.     

平坦色散高非线性光子晶体光纤的制备与实验

运用改进的全矢量有效折射率法(IFVEIM),课题组自行设计了一种在900 nm附近具有低平坦色散高非线性特性的光子晶体光纤.并且在改进工艺的基础上,采用中心抽真空挤压法对其进行了制备.虽然所制得光纤的结构参数与理论设计值存在一定的偏差,但其在所研究波段内色散值仅为0.5 ps/km/nm,非线性系数值则达到了35(W*km)-1,这在当前规则结构的纯硅光子晶体光纤中已经很高.最后,我们对其进行了非线性实验测试,其在400～1 400 nm的波段范围内展现出了宽平坦的超连续谱.     

Cluster-Based Saliency-Guided Content-Aware Image Retargeting

Straightforward image resizing operators without considering image contents (e.g., uniform scaling) cannot usually produce satisfactory results, while content-aware image retargeting aims to arbitrarily change image size while preserving visually prominent features. In this paper, a cluster-based saliency-guided seam carving algorithm for content-aware image retargeting is proposed. To cope with the main drawback of the original seam carving algorithm relying on only gradient-based image importance map, we integrate a gradient-based map and a cluster-based saliency map to generate a more reliable importance map, resulting in better single image retargeting results. Experimental results have demonstrated the efficacy of the proposed algorithm.     

通信系统中数字上变频技术的研究与设计

为了将通信系统中数字基带信号调制到中频信号上,采用数字上变频技术,通过对数字I、Q两路基带信号进行FIR成形滤波、半带插值滤波、数字混频处理得到正交调制后的中频信号,最后经MATLAB仿真分析得到相应的时域和频域图,来验证电路设计的有效性。     

基于混合三角变异差分进化算法的平面稀疏阵列约束优化

针对旁瓣零陷凹面约束的稀疏平面阵列优化及算法早熟等问题,该文基于参数自适应的思想,提出一种混合三角变异差分进化算法。通过引入旁瓣零陷凹面约束矩阵,构建自适应惩罚函数,时变权重组合变异策略与交叉策略,提高算法前期全局搜索能力和后期收敛能力,最终实现峰值旁瓣电平和旁瓣零陷凹面的平面阵列约束优化。仿真结果表明,对比混合三角变异策略前的算法,该算法在完成稀疏阵列峰值旁瓣电平优化的同时,能在指定旁瓣区域完成零陷凹面设计,降低有源干扰影响。

     

An Investigation of Microstructure and Microhardness of Sn-Cu and Sn-Ag Solders as Functions of Alloy Composition and Cooling Rate

The microstructure and microhardness of Sn-xAg and Sn-xCu solders were investigated as functions of alloy composition and cooling rate. The Ag compositions examined varied from 0.5 wt.% to 3.5 wt.%, while Cu varied from 0.5 wt.% to 2.0 wt.%. Three cooling rates were employed during solidification: 0.02°C/s (furnace cooling), about 10°C/s (air cooling), and 100°C/s or higher (rapid solidification). Sn grain size and orientation were observed by cross-polarization light microscopy and electron-backscattering diffraction (EBSD) techniques. The microhardness was measured to correlate the mechanical properties with alloy compositions and cooling rates. From this study, it was found that both alloy composition and cooling rate can significantly affect the Sn grain size and hardness in Sn-rich solders. The critical factors that affect the microstructure–property relationships of Sn-rich solders are discussed, including grain size, crystal orientation, dendrite cells, twin boundaries, and intermetallic compounds (IMC).     

ULSI中多层Cu布线CMP表面粗糙度的分析和研究

分析介绍了Cu层表面粗糙度对器件性能的影响以及超大规模集成电路中多层Cu布线CMP的作用机理,研究分析了碱性抛光液对Cu的表面粗糙度的影响因素,如磨料、氧化剂、pH值、表面活性剂等对表面粗糙度的影响。实验证明,在一定的抛光条件下,选用SiO2为磨料、双氧水为氧化剂的碱性抛光液可以有效降低Cu层的表面粗糙度,使之达到纳米级,得到良好的抛光效果,从而解决了超大规模集成电路多层Cu布线化学机械抛光中比较重要的技术问题。