Effect of interfacial fluorination on the electrical properties of the inter-poly high-k dielectrics

In this paper, the reliabilities and insulating characteristics of the fluorinated aluminum oxide (Al₂O₃) and hafnium oxide (HfO₂) inter-poly dielectric (IPD) are studied. Interface fluorine passivation has been demonstrated in terminating dangling bonds and oxygen vacancies, reducing interfacial re-oxidation and smoothing interface roughness, and diminishing trap densities. Compared with the IPDs without fluorine incorporation, the results clearly indicate that fluorine incorporation process is effective to improve the insulating characteristics of both the Al₂O₃ and HfO₂ IPDs. Moreover, fluorine incorporation will also improve the dielectric quality of the interfacial layer. Although HfO₂ possesses higher dielectric constant to increase the gate coupling ratio, the results also demonstrate that fluorination of the Al₂O₃ dielectric is more effective to promote the IPD characteristics than fluorination of the HfO₂ dielectric. For future stack-gate flash memory application, the fluorinated Al₂O₃ IPD undoubtedly possesses higher potential to replace current ONO IPD than the fluorinated HfO₂ IPD due to superior insulating properties.     

基于DSP的无背景模型车流量检测

针对车流量检测中遇到光照变化、树阴、树枝摇动等一系列问题,在运动物体法,背景建模法和时间差分法的基础上,提出了一种基于DSP的无背景模型的新型车流量检测方法。笔者依次使用基于块的帧差法、双重前景融合法、基于纹理对象分割法、假前景滤波法对车流量进行检测。经实验验证,采用无背景模型算法能成功有效地检测车流量,检测准确率达88%,提高了车流量检测的精度。     

NLOS Identification for Localization Based on the Application of UWB

Wireless Personal Communications - Ultra-wide bandwidth (UWB) transmission is a promising technology for localization systems, due to its power efficiency, strong penetrability, and robust...     

ZnO纳米线光学特性测试的倏逝波耦合

使用纳米氧化硅光纤探针,利用倏逝波耦合方法,将紫外到红外的激光成功地耦合进单根ZnO纳米线,耦合效率可达25%.实验观测了单根纳米线的荧光特性,发现ZnO纳米线光传输损耗很低.研究证明:采用透镜聚焦激发纳米线发光的传统耦合方法,只能使用特殊激发波长的光;而倏逝波耦合方法具有高效、适用性强的特点,在半导体纳米线和纳米带的光学特性研究中有广泛的应用前景.     

H-SPREAD: a hybrid multipath scheme for secure and reliable data collection in wireless sensor networks

Communication security and reliability are two important issues in any network. A typical communication task in a wireless sensor network is for every sensor node to sense its local environment, and upon request, send data of interest back to a base station (BS). In this paper, a hybrid multipath scheme (H-SPREAD) to improve both the security and reliability of this task in a potentially hostile and unreliable wireless sensor network is proposed. The new scheme is based on a distributed N-to-1 multipath discovery protocol, which is able to find multiple node-disjoint paths from every sensor node to the BS simultaneously in one route discovery process. Then, a hybrid multipath data collection scheme is proposed. On the one hand, end-to-end multipath data dispersion, combined with secret sharing, enhances the security of the end-to-end data delivery in the sense that the compromise of a small number of paths will not result in the compromise of a data message in the face of adversarial nodes. On the other hand, in the face of unreliable wireless links and/or sensor nodes, alternate path routing available at each sensor node improves the reliability of each packet transmission significantly. The extensive simulation results show that the hybrid multipath scheme is very efficient in improving both the security and reliability of the data collection service seamlessly.     

Influence of oxygen content on the crystallinity of MgO layers in magnetic tunnel junctions

With RF sputtering process, Si/Si02/Ta/Ru/Ta/CoFeB/MgO/CoFeB/Ta/Ru structure has been grown on Si （100） substrate. Attempting different targets and adjusting the oxygen dose, the crystallization quality of the MgO layer is studied. The X-ray diffraction measurements demonstrate that crystal structure and crystallization quality of MgO layers are related to the type of target and concentration of oxygen in sputtering process. With the method sputtering Mg in an ambient flow of oxygen, not only the crystallization quality of a normal MgO layer with lattice constant of 0.421 nm is improved, but also a new MgO crystal with lattice constant of 0.812 nm is formed and the perpendicular magnetic anisotropy of CoFeB is enhanced. Also it is found that crystallization quality for both the normal MgO and new MgO is more improved with MgO target and same oxygen dose, which means that this new method is helpful to form a new structure of MgO annealed at 400 ℃ in vacuum. with lattice constant of 0.812 nm. All of the samples were     

A green-switch controller IC for cascade buck–boost converter with seamless transition over entire input and load range

To raise the utilization ratio of lithium-ion battery in portable devices, a novel green-switch controller IC is proposed to constitute a 4-switch cascade buck–boost prototype, which is capable of outputting non-inverting step down and step up voltages. According to the relations between the input and output voltages through duty ratio, a finite state machine automatically determines the work method of converter namely buck method, boost method or transition method by combining peak and valley current programmed mode so as to improve the line regulation over the entire input voltage range. A three-phase seamless transition method is introduced into the controller. Its additional advantage is to lower output ripples. Furthermore, a special burst mode is added to reduce the power consumption during light-load operation. An elaborately designed circuitry and rigorous stability analysis further improves the seamless performance. The controller IC is designed and fabricated in 1.5 μm BCD (Bipolar-CMOS-DMOS) technology with an area of 8.75 mm² and applied to a 2.7 V–4.2 V/3.3 V, maximum output power 1.65 W buck–boost converter. It features over 90% conversion efficiency during normal application and still remains over 80% under standby mode. The experimental results show that all functional and performance targets are successfully achieved as expected.     

9μm截止波长128×128 AlGaAs/GaAs量子阱红外焦平面探测器阵列

报道了128×128 AlGaAs/GaAs量子阱红外焦平面探测器阵列的设计和制作.采用金属有机化学气相淀积外延技术生长外延材料,并在GaAs集成电路工艺线上完成工艺制作.为得到器件参数,设计制作了台面尺寸为300μm×300μm的大面积测试器件;77K下2V偏压时暗电流密度为1.5×10-3A/cm2;80K工作温度下,器件峰值响应波长为8.4μm,截止波长为9μm,黑体探测率DB 为3.95×108(cm·Hz1/2)/W.将128×128元 AlGaAs/GaAs量子阱红外焦平面探测器阵列芯片与相关CMOS读出电路芯片倒装焊互连,在80K工作温度下实现了室温环境目标的红外热成像,盲元率小于1%.     

Efficient three‐party password‐based key exchange scheme

In three‐party password‐based key exchange protocol, a client is allowed to share a human‐memorable password with a trusted server such that two clients can negotiate a session key to communicate with each other secretly. Recently, many three‐party password‐based key exchange protocols have been developed. However, these proposed schemes cannot simultaneously achieve security and efficiency. Based on elliptic curve cryptography (ECC), this paper will propose a new simple three‐party password‐based authenticated key exchange scheme. The proposed method not only reduces computation cost for remote users and a trusted server but also is more efficient than previously proposed schemes. It is better suited for resource constrained devices, such as smart cards or mobile units. Copyright © 2010 John Wiley & Sons, Ltd.     

提取光栅耦合的高电子迁移率晶体管中的太赫兹辐射

借助于傅立叶光谱仪,在具有耦合光栅的高电子迁移率晶体管中观察到了波长在400um左右的微弱的太赫兹辐射。同时使用了一种调制探测技术,从而使得太赫兹辐射的绝对功率能够被提取计算出来。并且发现器件的太赫兹辐射功率正比于源漏电流,而黑体辐射功率则与器件电功率有密切关系。此外,太赫兹辐射对于源漏偏置电压及栅压的依赖性,说明太赫兹辐射是由加速电子与光栅的相互作用而引起的。