基于单根氧化锌纳米线的场效应管的光电特性研究

本文介绍了一种基于单根氧化锌纳米线场效应管的制备方法,用XRD和SEM分析了样品的结构和形貌,测试了它的输出特性曲线和转移特性曲线.当Vds=2 V时,测得场效应管的开启电压Vgt=-16.2 V;计算得到低频跨导gm=46.6nS.在Vgs=0 V时,测得一维ZnO纳米线的载流子浓度n=1.15×108 cm-1,电子迁移率μe=14.4 cm2/Vs,电导率σ=0.26 Ω-1 cm-1.该场效应管的上限截止频率fH=1585 Hz,漏源极间电容C=25.4 pF.本文还对基于单根氧化锌纳米线的场效应管的光电灵敏度和光电时间响应进行了测试分析.     

合成和表征NiFe2O4纳米线阵列

采用真空灌注结合溶胶-凝胶和氧化铝模板法,在多孔氧化铝模板中制备了平均直径为50 nm的NiFe2O4纳米线阵列.X射线衍射结果显示所制备的纳米线是纯相的NiFe2O4纳米线,透射电镜和电子衍射的结果显示已制备的纳米线是多晶的且表面光滑,场发射扫描电镜图片显示纳米线是大面积且平行有序的、纳米线的长度和所用的氧化铝模板的厚度相当.磁测量的结果显示此纳米线阵列有形状各向异性,同块状材料相比矫顽力有所增强.对纳米线的生长机理做了简单的讨论.     

Perpendicular GMI Effect in Meander NiFe and NiFe/Cu/NiFe Film

We have evaluated the perpendicular giant magnetoimpedance effect (GMI) in both NiFe and NiFe/Cu/NiFe films with meander geometry in the $>$1 MHz high-frequency range. With the magnetic field, the perpendicular GMI effect shows an intense GMI peak value at a certain field. This effect is comparable to the longitudinal GMI effect in both profile and peak value amplitude. The experimental results correspond well with the predictions of a single-domain rotational magnetization model. These findings demonstrate that the deflection of the anisotropy to a perpendicular direction plays an important role in the perpendicular GMI effect.      

Effect of Gamma Irradiation on Dynamics of Charge Exchange Processes between Single Trap and Nanowire Channel

In the present study, transport properties and single trap phenomena in silicon nanowire (NW) field‐effect transistors (FETs) are reported. The dynamic behavior of drain current in NW FETs studied before and after gamma radiation treatment deviates from the predictions of the Shockley–Read–Hall model and is explained by the concept taking into account an additional energy barrier in the accumulation regime. It is revealed that dynamics of charge exchange processes between single trap and nanowire channel strongly depend on gamma radiation treatment. The results represent potential for utilizing single trap phenomena in a number of advanced devices.     

Influences of Extra Magnets on Giant Magnetoimpedance Effect in Amorphous Wires

Adjacent extra magnets can induce an additional impedance to an amorphous wire. We have studied the additional impedance passing through a magnetic ring and found that it is related to the electromagnetic characteristics, shapes, and locations of the extra magnet and the frequency of the ac excitation, regardless of the amorphous material properties and the extra magnetic field conditions. According to our theoretical analysis, the additional impedance severely reduces the magnetoimpedance change of the amorphous wire and destroys the giant magnetoimpedance characteristic. We therefore propose a return structure to diminish the additional impedance. Our experiments measured the impedances of an amorphous wire, a Cu wire, and the return structure with a variety of extra magnetic fields. The results confirmed the characteristics of the additional impedance and verified the effectiveness of the return structure.      

Scientists Make Single-Mode Laser Out of a Single Nanowire

Although lasers come in all shapes and sizes,one of the most recent laser designs is especially intriguing,since it’s madeof just a single nanowire. Due to its small size and simplicity,the single-nanowire laser could be used as a nanoscale coherentlight source for applications in optical communications,sensing,and signal processing.     

Dark Count Suppression in Superconducting Nanowire Single Photon Detectors

One of the important performance parameters of superconducting nanowire single photon detectors (SNSPD) is the dark count rate. Dark counts are related to thermally-activated hopping of magnetic vortices across the nanowire. We present an experimental analysis of how the thermal coupling of the NbN SNSPD to the heat sink affects the dark count rate. It was found that the rate decreases with the increase in coupling strength while the detection efficiency remains almost constant.     

钴基软磁非晶合金的巨磁阻抗效应研究进展

介绍了钴基软磁非晶合金丝与薄带的制备方法,重点讨论了频率、磁各向异性等因素对巨磁阻抗效应的影响.对非晶合金的巨磁阻抗效应传感器的应用进行了展望.     

Giant Magnetoimpedance Effect: Concept and Prediction in Amorphous Materials

Giant magneto impedance (GMI) effect was experimentally measured on as-cast, post-production and coated with chemical technique amorphous wire and ribbon materials consisted of varied chemical composition over a frequency range from 0.1 to 8 MHz under a static magnetic field between ?8 and +8 kA/m. The results show that each amorphous sample has a certain operational frequency for which the GMI effect has maximum magnitude and the other parameters such as annealing and coating have a significant influence on the GMI effect. It is believed that the domain structure and wall mechanism in the material are responsible for this behaviour. A 3-node input layer, 1-node output layer artificial neural network (ANN) model with three hidden layers including 30 neurons and full connectivity between the nodes was developed. A total of 1600 input vectors obtained from varied treated samples was available in the training data set. After the network was trained, better results were obtained from the network formed by the hyperbolic tangent transfer function in the hidden layers, there was a sigmoid transfer function in the output layer and we predicted the GMI. Comparing the predicted values obtained from the ANN model with the experimental data indicates that a well-trained neural network model provides very accurate results.     

电流退火对CoFeSiB非晶丝和薄带的巨磁阻抗效应比较

采用熔融抽拉法和单辊急冷法分别制备了Co68.25Fe4.5Si12.25B15非晶丝和薄带。测量了制备态下两者的巨磁阻抗(GMI)效应,发现非晶丝的GMI比率高于薄带。研究了不同电流密度退火后非晶丝和薄带的GMI效应,结果发现ΔΖ/Ζ=[Z(H)-Z(H=0)]/Z(H=0)都明显上升,且非晶薄带数值更大;当电流密度等于0.96×107A/m2时,薄带的这一比率最大达到410%,磁场灵敏度达到5.1%/(A/m)。分析了出现上述现象的原因。     

Single Crystal Fe Nanowire Arrays Encapsulated by SiO2 Nanotubes

Aligned silicon dioxide nanotubes with diameter of 60-70 nm were synthesized inside the nanoholes of an anodic AI membrane (AAM) template by pressure impregnating the AAM pores with the SiO_2 sol. The Si0_2 nanotubes with different wall thickness were produced by repeating the process. Using the second-order template of porous AAM with silicon dioxide nanotubes, it was fabricated the nanostructure of Fe nanowires encapsulated by SiO_2 nanotubes by electrochemical deposition. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the nanotubes and nanocables are compact, continuous and uniform. Selected area electron diffraction (SAED) pattern shows the Fe nanowire is a single crystal. The magnetic properties of these samples were checked by a vibrating sample magnetometer (VSM). The coercivities of the samples are greatly improved compared to the corresponding bulk materials.     

Fe84Zr7B9薄带中的巨磁阻抗效应

详细研究了Ｆｅ８４Ｚｒ７Ｂ９薄带中的巨磁阻抗效应。研究了退火工艺对巨磁阻抗效应的影响。发现６００℃退火２０ｍｉｎ的Ｆｅ８４Ｚｒ７Ｂ９薄带在１．５ＭＨｚ下的（Ｚｍａｘ（Ｈ）－Ｚ（５２００Ａ／ｍ）／Ｚ（５２００Ａ／ｍ）达到１５２％。同时我们还测量磁导率随磁场的变化关系,研究了不同退火工艺下材料的磁导率,发现材料磁导率值与巨磁阻效应的大小紧密相关。