Triple‐Shape Polymeric Composites (TSPCs)

In this paper, the fabrication and characterization of triple‐shape polymeric composites (TSPCs) that, unlike traditional shape memory polymers (SMPs), are capable of fixing two temporary shapes and recovering sequentially from the first temporary shape (shape 1) to the second temporary shape (shape 2), and eventually to the permanent shape (shape 3) upon heating, are reported. This is technically achieved by incorporating non‐woven thermoplastic fibers (average diameter ～760 nm) of a low‐T_m semicrystalline polymer into a T_g‐based SMP matrix. The resulting composites display two well‐separated transitions, one from the glass transition of the matrix and the other from the melting of the fibers, which are subsequently used for the fixing/recovery of two temporary shapes. Three thermomechanical programming processes with different shape fixing protocols are proposed and explored. The intrinsic versatility of this composite approach enables an unprecedented large degree of design flexibility for functional triple‐shape polymers and systems.     

Self‐Powered Trace Memorization by Conjunction of Contact‐Electrification and Ferroelectricity

Triboelectric nanogenerator (TENG) is a newly invented technology that can effectively harvest ambient mechanical energy from various motions with promising applications in portable electronics, self‐powered sensor networks, etc. Here, by coupling TENG and a thin film of ferroelectric polymer, a new application is designed for TENG as a self‐powered memory system for recording a mechanical displacement/trace. The output voltage produced by the TENG during motion can polarize the dipole moments in the ferroelectric thin film. Later, by applying a displacement current measurement to detect the polarization density in the ferroelectric film, the motion information of the TENG can be directly read. The sliding TENG and the single‐electrode TENG matrix are both utilized for realizing the memorization of the motion trace in one‐dimensional and two‐dimensional space, respectively. Currently, the ferroelectric thin film with a size of 3.1 mm² can record a minimum area changing of 30 mm² and such resolution can still be possibly improved. These results prove that the ferroelectric polymer is an effective memory material to work together with TENG and thereby the fabricated memory system can potentially be used as a self‐powered displacement monitor.     

High Performance Flexible Nonvolatile Memory Based on Vertical Organic Thin Film Transistor

Flexible floating‐gate organic transistor memory (FGOTM) is a potential candidate for emerging memory technologies. Unfortunately, conventional planar FGOTM suffers from weak driving ability and insufficient mechanical flexibility, which limits its commercial application. In this work, a novel flexible vertical FGOTM (VFGOTM) is reported. Benefitting from new vertical architecture, VFGOTM provides ultrashort channel length to afford an extremely high current density. Meanwhile, VFGOTM devices exhibit excellent memory performance and outstanding retention property. The memory properties of VFGOTM devices are comparable or even better than traditional planar FGOTM and much better than the reported organic nonvolatile memory with vertical transistor structures. More importantly, organic nonvolatile memory with vertical transistor structures is investigated for the first time on a flexible substrate. The results show that VFGOTM architecture allows vertical current flow across the channel layer to effectively eliminate the effect of mechanical bending during current transport, which significantly improves the mechanical stability of the flexible VFGOTM. Hence, with a combination of excellent driving ability, memory performance, and mechanical stability, VFGOTM devices meet the practical requirements for high performance memory applications, which have great potential for the application in a wide range of flexible and wearable electronics.     

PUF‐based solutions for secure communications in Advanced Metering Infrastructure (AMI)

Advanced metering infrastructure (AMI) provides 2‐way communications between the utility and the smart meters. Developing authenticated key exchange (AKE) and broadcast authentication (BA) protocols is essential to provide secure communications in AMI. The security of all existing cryptographic protocols is based on the assumption that secret information is stored in the nonvolatile memories. In the AMI, the attackers can obtain some or all of the stored secret information from memories by a great variety of inexpensive and fast side‐channel attacks. Thus, all existing AKE and BA protocols are no longer secure. In this paper, we investigate how to develop secure AKE and BA protocols in the presence of memory attacks. As a solution, we propose to embed a physical unclonable function (PUF) in each party, which generates the secret values as required without the need to store them. By combining PUFs and 2 well‐known and secure protocols, we propose PUF‐based AKE and BA protocols. We show that our proposed protocols are memory leakage resilient. In addition, we prove their security in the standard model. Performance analysis of both protocols shows their efficiency for AMI applications. The proposed protocols can be easily implemented.     

黑匣子-X25045与时钟芯片DS12887在网络智能型家居服务器中的应用

第一时间将所发生事件的时间日期存储起来,往往是系统设计,被存储起来的时间日期,对于分析、了解所发生事件的原因将起到重大作用.从系统运行的稳定性、可靠性出发,设计一种以X25045为存储元件,DS12887为计时元件,EW78E58单片机为核心,OCMJ4×8C液晶显示器为显示器件的事件存储系统.该系统已在网络智能型家居服务器中应用,其运行稳定、可靠,电路设计简单实用.     

一种相变存储器读出电路及其快速读出方法

针对大规模相变存储器所具有的寄生电容大、可能出现读破坏现象等特性,提出了一种读电压模式的相变存储器读出电路及其快速读出方法。基于SMIC 40nm CMOS工艺的仿真结果表明,在2.5V电源电压下,该方法可以在90ns的读出周期内正确读出位线寄生电容为30pF的存储单元数据,同时,该读出周期随位线寄生电容的减小而减小。另外,该方法可以和传统的Burst等快速读出方式并存,非常适用于带数据预读机制的高端存储器技术。     

CF4预处理后热生长薄栅氧漏电流及势垒研究

嵌入式Flash Memory要求低的工作电压．采用反应离子刻蚀技术，用CF4气体在低功率下对硅片做预处理，再热生长薄氧化层，从而在氧化层中引入F，降低氧化层势垒:势垒高度从3.05eV降低到2.5eV，隧穿电流增加，从而可以在低压下提高Flash Memory的编程效率．     

一种适用于概率LDPC译码器的双路更新边缘存储器

针对采用传统边缘存储器结构的概率低密度奇偶校验(Low Density Parity Check,LDPC)译码器中仍存在锁存问题的现象,借鉴全并行Turbo译码器中的多路更新策略,提出了一种增强的变量节点和校验节点双路更新边缘存储器结构。利用双路更新结构引入的增强随机选择特性,可以显著降低概率迭代译码过程中的锁存现象。仿真分析表明,相比于单路更新结构,采用双路更新边缘存储器结构的概率LDPC译码器能够在误比特率接近10-4量级处获得0.4 dB左右的译码性能增益,同时也能够显著降低迭代译码周期数量,提升译码速率。     

低电场应力下闪速存储器的退化特性

基于负栅源边擦除的闪速存储器存储单元,研究了形成应力诱生漏电流的三种导电机制,同时采用新的实验方法对引起瞬态和稳态电流的电压漂移量进行了测量.并利用电容耦合效应模型对闪速存储器存储单元的可靠性进行了研究,结果表明,在低电场应力下,其可靠性问题主要由载流子在氧化层里充放电引起.