有机半导体材料并五苯薄膜的生长

优化有机晶体的生长工艺是获得性能优良的有机场效应管(OFET)的重要基础。以热氧化后的硅片为衬底,用真空蒸镀的方法制备了有机半导体材料并五苯薄膜,通过X射线衍射和原子力显微镜对薄膜的生长晶体结构及形貌等进行了分析,讨论了薄膜制备过程中的诸多因素对晶体生长的影响。     

Co-Si多层膜在稳态热退火中的固相界面反应

超高真空条件下,采用电子束蒸发工艺在Si(111)衬底上交替蒸镀200A的Co和Si薄膜形成多层膜结构,在恒温炉中作稳态热退火,然后用XRD、RBS及AES等技术作分析,研究了Co-Si多层膜固相反应的相序,用四探针测量了反应生成的钴硅化物的电阻率。结果表明,随着退火温度的升高,淀积在Si(111)上的Co膜逐步转化为Co_2Si、CoSi和CoSi_2,最后完全转化为CoSi_2。在比单层膜低得多的温度下退火获得了电阻率较低、表面形态良好、晶粒很大的CoSi_2薄膜材料。     

碲化铅薄膜电学特性的研究

用真空蒸镀法制备了Pb49Te51薄膜,并对薄膜的显微结构、导电类型和电阻率等电学特性及热处理对薄膜性能的影响进行了研究。结果表明:热处理对薄膜结构和性能影响很大,热处理后薄膜呈铜黄色,晶粒有明显取向,其形状为片状,且晶粒尺寸变大为300~400nm;薄膜为p型半导体薄膜,其电阻率4.624×10–2Ω.cm比晶体材料12.410×10–2Ω.cm大。     

电子束蒸发沉积TiN薄膜的电学特性研究

采用TCP(Transverse coupled plasma)等离子体辅助电子枪蒸镀技术,在玻璃衬底上制备了TiN薄膜。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究了不同工艺条件对薄膜晶体结构和表面形貌的影响;用四探针法测量薄膜的电阻率变化。结果表明,所制备的TiN薄膜在(111)晶面有择优取向。与金属薄膜类似,TiN薄膜的平均表面粗糙度与电阻率之间存在近似线性关系,并且电阻率随残余应力增大而增大。     

八羟基喹啉镉薄膜制备及其光学特性

用真空蒸镀方法,在玻璃衬底上制备了衬底温度不同的八羟基喹啉镉薄膜.XRD分析表明,八羟基喹啉镉薄膜呈多晶态,且衬底温度越高,衍射峰越强,薄膜的结晶性能逐渐变好,结晶晶粒尺度也越大.AFM研究表明,衬底温度升高,薄膜表面形貌越均匀有序,质量变好.MM-16相调制型椭圆偏振光谱仪研究发现,衬底温度升高导致反蒸发增强,薄膜生长速率减小,随着入射光波长的增加,薄膜的折射率和消光系数逐渐减小.随着衬底温度升高,因薄膜晶粒尺度增大,折射率和消光系数也增大;并给出了它们的变化范围.     

ZnO纳米晶须的形态控制及其结构表征

采用激光分子束外延法先在Si(111)衬底上制备Zn薄膜,在不同的氧气体积流量和生长温度下,用热蒸发法在镀有Zn薄膜的Si(111)衬底上制备了不同形貌的ZnO纳米晶须。分别用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)对样品的成分、微结构和形貌进行了表征。Zn薄膜在高温下被氧化,并为晶体生长提供均匀的成核点,有利于形成一定大小和数量的ZnO晶核。研究结果表明,氧气体积流量和生长温度对ZnO纳米晶须的形貌有一定的影响。     

八羟基喹啉镉薄膜制备及其光学特性

用真空蒸镀方法,在玻璃衬底上制备了衬底温度不同的八羟基喹啉镉薄膜.XRD分析表明,八羟基喹啉镉薄膜呈多晶态,且衬底温度越高,衍射峰越强,薄膜的结晶性能逐渐变好,结晶晶粒尺度也越大.AFM研究表明,衬底温度升高,薄膜表面形貌越均匀有序,质量变好.MM-16相调制型椭圆偏振光谱仪研究发现,衬底温度升高导致反蒸发增强,薄膜生长速率减小,随着入射光波长的增加,薄膜的折射率和消光系数逐渐减小.随着衬底温度升高,因薄膜晶粒尺度增大,折射率和消光系数也增大;并给出了它们的变化范围.     

ICP等离子体辅助对共蒸发法制备Cu-Zn-Sn金属前驱体和CZTS薄膜的优化

本文在传统蒸发沉积制备工艺的基础上, 引入ICP (Inductively coupled plasma)等离子体辅助技术, 在玻璃衬底上制备了铜锌锡(CZT) 金属前驱体. 在蒸镀过程中保持衬底温度为220oC, 气压为6.5×10-2Pa, 氩气放电辅助蒸发舟蒸镀. 采用Langmuir探针测量Ar气等离子体参数,等离子体密度和电子温度随着放电功率的增加而增大. 改变等离子体的放电功率, 探究功率对CZT前驱体薄膜结构和形态的影响. 通过扫描电子显微镜(SEM),能谱分析(EDS)和X射线衍射(XRD)进行表征. 结果表明: 等离子体的引入可以改善传统蒸镀法制备的前驱体中Zn缺失的现象; 使得金属前驱体的晶粒尺寸变大, 排列致密, 结晶程度较高.最后,制备Cu2ZnSnS4 (CZTS)薄膜并测量其性能,进一步证明ICP可以优化薄膜的生长.     

沉积温度对PbTe薄膜结构和光学性能的影响

采用电阻热蒸镀法,分别以不同的沉积温度在锗基底上制备了PbTe薄膜。用X射线衍射仪(XRD)、原子力显微镜(AFM)和红外光谱测试仪(System2000)表征了不同沉积温度下薄膜的微结构和光学特性.结果表明,沉积温度对PbTe薄膜的结构、择优取向、生长方向、晶粒大小、禁带宽度以及短波吸收限均有明显影响.     

Co—Si多层膜的透射电镜研究

本文用TEM技术系统地研究了超高真空中在Si(111)衬底上交替蒸镀Co、Si形成的多层薄膜,在稳态热退火过程中硅化物的生长规律,观察生成硅化物的成分和晶粒度、薄膜的表面形态和界面特征等微结构的变化。结果表明,随着退火温度的升高Co膜逐渐转化为Co_2Si、CoSi和CoSi_2,硅化物晶粒的大小随退火温度的升高而增大,340—370℃退火后在Co耗尽前Co_2Si和CoSi能同时生长(三相共存)。结合XRD分析,证实了上述结果的可靠性。     

Patterned magnetic nanostructures and quantized magnetic disks

Nanofabrication, offering unprecedented capabilities in the manipulation of material structures and properties, opens up new opportunities for engineering innovative magnetic materials and devices, developing ultra-high-density magnetic storage, and understanding micromagnetics. This paper reviews the recent advances in patterned magnetic nanostructures, a fast-emerging field, including (1) state-of-the-art technology for patterning of magnetic nanostructures as small as 10 nm; (2) engineering of unique magnetic properties (such as domain structures, domain switching, and magnetoresistance) by patterning and controlling the size, shape, spacing, orientation, and compositions of magnetic materials; (3) quantized magnetic disks-a new paradigm for ultra-high-density magnetic storage based on patterned single-domain elements that have demonstrated a storage density of 65 Gb/in² (nearly two orders of magnitude higher than that in current commercial magnetic disks) and a capability of 400 Gb/in² ; (4) novel magnetoresistance sensors based on unique properties of magnetic nanostructures; (5) other applications of nanoscale patterning in magnetics such as the quantification of magnetic force microscopy (MFM) and a new ultra-high-resolution MFM tip; and (6) sub-10-nm imprint lithography-a new low-cost, high-throughput technology for manufacturing magnetic nanostructures     

低频脉冲磁场中磁屏蔽体磁饱和效应的试验研究

针对磁屏蔽体在低频脉冲磁场环境中可能存在的磁饱和问题，利用试验方法开展了磁饱和效应研究，证实了常规工程屏蔽体可在低频脉冲磁场环境中达到磁饱和状态，并通过观测屏蔽效能的变化获得了磁饱和规律，同时分析了磁饱和效应对屏蔽效能的影响及其与屏蔽体的材料磁导率、壳体厚度、外形尺寸等参数的关系. 研究表明:磁屏蔽体屏蔽效能在磁饱和效应影响下，呈现出明显的动态变化特点，具有与屏蔽壳体磁导率类似的变化趋势；壳体厚度2 mm以内、长宽高为2 m×2 m×2 m左右的屏蔽体在上升时间为300 μs、持续时间为1.2 ms的磁场环境中，达到磁饱和状态的磁化场强度约为10 mT，其磁饱和难易程度与磁导率及外形尺寸负相关，与壳体厚度正相关. 试验研究结果与理论分析结论一致，可为磁屏蔽体的科学合理设计提供参考，具有较高的工程应用价值.     

Electronically tunable magnetic patch antennas with metal magnetic films

AS new type of electronically tunable magnetic patch antennas with metal magnetic films was designed, fabricated, and tested at 2.1 GHz. The magnetic patch antennas showed an enhanced bandwidth of 50% over the non-magnetic patch antennas, a significantly enhanced directivity, and a large tunability of the radiation intensity of 4.23 dB at a low applied magnetic field of ~20 Oe     

Picosecond magnetic spectroscopy of two- and three-dimensionaldiluted magnetic semiconductors

The authors have developed a novel type of magnetic spectroscopy which relies on an integrated multichip SQUID (superconducting quantum interference devices) microsusceptometer to obtain nearly quantum-limited spin resolution. The susceptometer, including two DC SQUIDs, pickup loops, and field coils, was fabricated using VLSI technology to achieve an unprecedented scale of magnetic sensitivity, optimized for the study of microscopic samples or thin layers. Furthermore, in combination with an ultrafast pulsed laser system, measurements can be made at picosecond time scales, providing an understanding of the dynamics of the magnetic phenomena in these materials and the effects of quantum confinement on magnetic behavior     

Weak magnetic field pattern detection by CMOS magnetic latch

A CMOS magnetic latch for digital magnetic field detection is reported. It is based on a single split-drain magnetic field-effect transistor with a positive feedback imported by a pair of lateral floating gates. The magnetic latch achieves its maximum magnetic sensitivity when latch-up takes place. A linear equation is used to model the positive feedback and the latch-up process. By imposing a reset-evaluation mechanism, the magnetic latch is evaluated for digital magnetic pattern detection. Experimental results show that the minimum detectable magnetic flux density for the magnetic latch could be down to less than 0.1 mT with low bit error rate.     

磁保持继电器空间磁干扰敏感位置的研究

开关器件的快速动作具有较高的du/dt与di/dt,使其本身成为干扰源对周围设备产生电磁干扰,文章以外加磁钢模拟磁保持继电器上方可能存在的干扰源,运用有限元分析软件建立其静态干扰模型.基于不同位置外部磁钢对衔铁组件所受力矩的影响具有极大值,将黄金分割法应用于对磁保持继电器空间磁干扰敏感位置的求解.结果表明,与衔铁组件平行的磁场方向为磁干扰敏感方向,敏感方向下存在磁干扰最大位置即敏感位置.此外,进一步确定了空间磁干扰危险区间.     

Soft magnetic materials

The state of art is reviewed with an emphasis on recent research results and a view to identifying areas in which further developments in materials and processing might lead to even better properties and greater application of novel technology. Basis magnetic considerations are discussed, namely, B-H loop shape, core loss, magnetic anisotropy and annealing, and magnetostriction and stress effects. Materials and applications for power frequency devices are examined, covering core loss considerations, silicon steel development, metallic glasses, and high silicon materials. High-frequency and pulse applications, magnetic recording heads, and sensor and transducer applications are also discussed. Basic research questions and future directions with respect to core loss, magnetization, and stability are examined     

Gigabit-density magnetic recording

A tutorial on the principles of magnetic recording is given. The enormous rate of areal density increase for the past thirty years as well as the principal technological changes behind such sustained progress are outlined. The general issues involved in gigabit-density recording and the features that are common to both IBM'S and Hitachi's gigabit efforts are explored. The principal recording components, namely, the recording head and the medium, are considered, focusing on the problems encountered in designing, optimizing, and realizing them for gigabit-density applications. The performance of gigabit recording configurations from both IBM and Hitachi is reviewed. The performance limitations of these gigabit configurations and the prospects for further areal density extensions in magnetic recording are discussed     

Imaging magnetic fields

A scanning squid microscope (SSM) detects sub-nanotesla fields and nanoamperes of current with unsurpassed sensitivity. SSM can image magnetic fields at the surface of the sample under study. It is paving the way to an understanding of how materials that become superconducting at a rather high transition temperature do it. The author describes the SSM and how it is used to image the magnetic fields