基于金属掺杂ITO透明导电层的紫外LED制备

为降低ITO薄膜对紫外波段的光吸收,制备低电压高功率的紫外LED,研究了一种基于金属掺杂ITO透明导电层的365 nm紫外LED的制备工艺。利用1 cm厚的石英片生长了不同厚度ITO薄膜以及在ITO上掺杂不同金属的新型薄膜,并研究了在不同的退火条件下这种薄膜的电阻和透过率,分析了掺杂金属ITO薄膜的带隙变化。将这种掺杂的ITO薄膜生长在365 nm外延片上并完成电极生长,制备成14 mil×28 mil的正装LED芯片。利用电致发光（EL）设备对LED光电性能进行测试并对比。实验结果表明:掺Al金属的ITO薄膜能够相对ITO薄膜的带隙提高0.15 eV。在600℃退火后,方块电阻降低6.2 Ω/□,透过率在356 nm处达到90.8%。在120 mA注入电流下,365 nm LED的电压降低0.3 V,功率提高14.7%。ITO薄膜掺金属能够影响薄膜带隙,改变紫光LED光电性能。     

对电感电容损耗电阻的研究

电感电路和电容电路在电子技术的滤波电路中有着重要作用,损耗电阻的大小是设计滤波电路参数的重要依据．人们通常在讨论电感和电容特性时,都把电感和电容当作纯电抗性元件,认为在低频段它们不存在损耗电阻,只有在10。Hz以上的高频范围内才有损耗电阻存在,事实是这样吗？事实并非如此,本文试图通过实验测试分析电感电容在10^3～10^4Hz的频率范围内它们的损耗电阻不能忽略,而且电感的损耗电阻随着频率的升高而增大,电容的损耗电阻随着频率的升高而降低．     

高重复频率锁模光纤激光器及其超连续谱产生

设计并实验研究了一种结构简单的主动调制锁模高重复频率窄脉宽光纤激光器。采用窄线宽连续激光调制4 GHz高重频后,通过拉曼增益孤子压缩效应将脉宽由27 ps压窄至2.6 ps。该高重频锁模激光泵浦一段300 m长高非线性光纤,同时脉冲被展宽至7.4 ps。产生的超连续谱平坦度20 dB宽带可达250 nm,功率波动为±0.2 dB。     

基于3D-EEMs和PARAFAC的土壤渗滤系统DOM垂直分布特征

利用三维荧光光谱(3D-EEMs)和平行因子分析(PARAFAC)的方法研究了土壤渗滤系统处理模拟高氨氮废水中溶解性有机物(DOM)的垂直分布特征。试验在一个中试规模的土壤渗滤系统中进行,反应器自上而下每隔30 cm设置一个采样口,采集的样品通过PARAFAC识别出系统不同点位的DOM具有四个荧光组分,包括两个类腐殖质物质(C1,C2)、2个类蛋白物质(C3,C4)。相关性分析显示,四种荧光组分与多数理化指标呈现极显著性正相关关系,可以用荧光组分浓度间接表征系统对氮、磷等营养元素的去除效果。对荧光组分浓度得分F_max分析得出,土壤渗滤系统中类酪氨酸最易降解,其次为类富里酸、类胡敏酸类物质,最难以降解的为类蛋白物质。     

Experimental demonstration of underwater optical wireless power transfer using a laser diode

We experimentally demonstrate an underwater optical wireless power transfer(OWPT) using a laser diode(LD)as a power transmitter. We investigate the characteristics of a solar cell and a photodiode(PD) as a power receiver. We optimize the LD, the PD, and the solar cell to achieve the maximum transfer efficiency. The maximum transfer efficiency of the back-to-back OWPT is measured as 4.3% with the PD receiver. Subsequently, we demonstrate the OWPT in tap and sea water. Our result shows an attenuation of 3 dB/m in sea water.     

Damage effect and mechanism of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

The damage effect and mechanism of the electromagnetic pulse(EMP) on the GaAs pseudomorphic high electron mobility transistor(PHEMT) are investigated in this paper. By using the device simulation software, the distributions and variations of the electric field, the current density and the temperature are analyzed. The simulation results show that there are three physical effects, i.e., the forward-biased effect of the gate Schottky junction, the avalanche breakdown, and the thermal breakdown of the barrier layer, which influence the device current in the damage process. It is found that the damage position of the device changes with the amplitude of the step voltage pulse. The damage appears under the gate near the drain when the amplitude of the pulse is low, and it also occurs under the gate near the source when the amplitude is sufficiently high, which is consistent with the experimental results.     

Thermodynamic and transport properties of spiro-(1,1')-bipyrrolidinium tetrafluoroborate and acetonitrile mixtures:A molecular dynamics study

Organic salts such as spiro-(1,1')-bipyrrolidinium tetrafluoroborate([SBP][BF4]) dissolved in liquid acetonitrile(ACN) are a new kind of organic salt solution,which is expected to be used as an electrolyte in electrical double layer capacitors(EDLCs).To explore the physicochemical properties of the solution,an all-atom force field is established on the basis of AMBER parameter values and quantum mechanical calculations.Molecular dynamics(MD) simulations are carried out to explore the liquid structure and physicochemical properties of [SBP][BF4] electrolyte at room temperature.The computed thermodynamic and transport properties match the available experimental results very well.The microscopic structures of [SBP][BF4] salt solution are also discussed in detail.The method used in this work provides an efficient way of predicting the properties of organic salt solvent as an electrolyte in EDLCs.     

Interplay of Rashba effect and spin Hall effect in perpendicular Pt/Co/MgO magnetic multilayers

The interplay of the Rashba effect and the spin Hall effect originating from current induced spin–orbit coupling was investigated in the as-deposited and annealed Pt/Co/MgO stacks with perpendicular magnetic anisotropy. The above two effects were analyzed based on Hall measurements under external magnetic fields longitudinal and vertical to dc current,respectively. The coercive field as a function of dc current in vertical mode with only the Rashba effect involved decreases due to thermal annealing. Meanwhile, spin orbit torques calculated from Hall resistance with only the spin Hall effect involved in the longitudinal mode decrease in the annealed sample. The experimental results prove that the bottom Pt/Co interface rather than the Co/MgO top one plays a more critical role in both Rashba effect and spin Hall effect.     

构建物理模型 切忌随心所欲

以不可压缩流体通过流管各截面的流量都相等这一连续性原理和“ 游乐园入口旁有一喷泉”这一实际 条件为依据, 评析2 0 1 6年高考河北省教育考试院印发的“ 试题与参考答案”理科综合能力测试第3 5( 2) ( i i )题中把 水柱强行视为圆柱体模型的错误做法, 并给出了适切模型和正确解法     

大气湍流对空间目标偏振成像探测的影响

为研究大气湍流对空间目标偏振成像探测准确度的影响,构建了大气湍流影响下的偏振成像探测模型,并对大气湍流导致的空间目标偏振度探测偏差进行仿真分析.通过对分时和同时偏振成像方式进行仿真,发现大气湍流会对空间目标偏振成像探测准确度造成明显影响,且对分时偏振成像探测准确度的影响明显大于同时偏振成像方式.通过自适应系统校正部分低阶像差,能明显减小大气湍流对偏振成像探测准确度的影响.为了兼顾图像信噪比和大气湍流影响下的偏振成像探测准确度,给出了一种结合分时和同时成像方式的改进偏振成像探测方式,大气湍流对其的影响略大于同时偏振成像方式,但该方式图像信噪比明显优于同时偏振成像方法.另外仿真分析发现,采用多帧图像叠加能效减小大气湍流带来的空间目标偏振成像探测偏差,在使用分时偏振成像方式时效果尤为明显.