Modulation of the spin transport properties of the iron-phthalocyanine molecular junction by carbon chains with different connection sites

Based on the non-equilibrium Green's function method combined with the density functional theory, the spin transport properties of an iron-phthalocyanine (FePc) molecule connected to two Au electrodes by carbon chains are investigated, and three kinds of connecting position between FePc molecule and carbon chains are considered. It is found that the spin filtering effect and the negative differential resistance (NDR) behavior in these systems can be achieved in the calculated bias region. However, the efficiency and the bias region of spin filtering are affected significantly by the connecting positions. The above results are explained by the spin-resolved transmission spectrum, electron transmitting path, molecular projected self consistent Hamiltonian state, and the local density of states (LDOS) analyses. Our calculations demonstrate a promising modification for developing molecule spintronic devices.     

Spin-filtering and rectifying effects for Al-doped zigzag-edged silicene nanoribbons with asymmetric edge hydrogenation

Spin transport features of the Al-doping zigzag-edged silicene nanoribbons (ZSiNRs) are investigated by using the nonequilibrium Green's function method and the spin-polarized density functional theory, where ZSiNRs are Si–H₂ bonded at one edge while Si–H bonded at the other to form an asymmetric edge hydrogenation. It is found that a perfect spin filtering effect (100%) in such ZSiNRs can be achieved in the calculated bias region. The rectifying performance of spin-polarized currents with a ratio larger than 10⁵ can be achieved by changing the position of the doping atoms. Moreover, the negative differential resistance (NDR) effect is also observed in the spin-polarized current. Our calculation suggests Al-doping ZSiNRs with the asymmetric edge hydrogenation hold promise for multifunctional spintronic devices.     

共振隧穿二极管的力电耦合特性

报道了微结构中共振隧穿二极管（RTD）的压阻效应. 分析并加工了四梁结构,其中RTD置于应力敏感区. 沿［110］晶向和［110］晶向的应力导致RTD电流-电压曲线的改变,即介观压阻变化,尤其是在微分负阻（NDR）区. 采用不同测试方法,研究了RTD的力电耦合特性,并获得了较相近的压阻系数为1E-9Pa-1.     

自组装Si量子点阵中室温共振隧穿及微分负阻特性

报道了自组装Si量子点(Si-QDs)阵列在室温下的共振隧穿及其微分负阻特性.在等离子增强化学气相沉淀系统中,采用layer-by-layer的淀积技术和原位等离子体氧化方法制备了Al/SiO2/Si-QDs/SiO2/Substrate双势垒结构.通过原子力显微镜和透射电子显微镜检测,证实所获得的Si-QDs阵列中Si量子点平均尺寸为6nm,并具有较好的尺寸均匀性(小于10%).在对样品的室温I-V和C-V特性的测量中,直接观测到由于Si量子点中分立能级而引起的共振隧穿和充电效应:I-V特性表现出显著的"微分负阻特性(NDR)";而CV特性中也同样观测到位置相对应、结构相似的峰结构,从而证实了I-V和C-V特性中的峰结构都同样来源于电子与Si量子点阵列中分离能级之间的共振隧穿和充电过程.进一步研究发现,Si量子点阵列中共振隧穿和NDR特性所特有"扫描方向"和"速率"依赖性及其机制,与量子阱的情况有所不同.通过所建立的主方程数值模型,成功地解释并重复了Si量子点阵中共振隧穿所特有的输运特性.     

一种新型结构的InGaP/GaAs负阻异质结晶体管

利用硅双基区晶体管（DUBAT）产生负阻的原理,针对HBT器件结构和MBE材料结构的特点,设计并研制出一种基区刻断结构的负阻型HBT (NDRHBT) . 经过特性和参数测试,证明此种NDRHBT具有显著的微分负阻效应,并发现负电流区负阻效应和光照可改变其I-V特性,器件模拟结果和测试结果基本一致.     

Na掺杂对C20H20分子的电子输运性质影响

利用第一性原理密度泛函理论和非平衡格林函数方法研究了Na@C₂₀H₂₀分子的电子输运性质. 计算结果显示它的I-V曲线在偏圧 V范围内表现出了较好的线性特性, 出现了明显的负微分电阻现象, 并得到其平衡电导为0.0101G₀. 通过与Li@C₂₀H₂₀分子对比分析, 发现掺杂Na不仅能提高C₂₀H₂₀分子的电子输运能力, 而且 关键词： 20H₂₀分子')" href="#">Na@C₂₀H₂₀分子 电子输运 负微分电阻     

半导体异质结中的实空间转移

实空间转移的机理不同于k空间转移,因而受到了广泛关注。实空间转移效应的器件是一种新型的半导体器件,有众多其它器件达不到的优点,如响应时间可达到ps级别、可以实现负阻效应等。为深入的理解半导体异质结中的实空间转移对实空间转移效应的基本原理以及它在相应器件上的应用进行了研究,概述了国际上的相关研究方向和研究进展,并提出研究思路和技术方案。     

DFT-NEGF study of transport properties and NDR behavior in fused furan and thiophene dimmers

The nonequilibrium Green's function approach in combination with density-functional theory is used to perform quantum mechanical calculations of the electron transport properties of furan and thiophene dimmers. Both the molecular systems have two S-linker and translated into the Gold junction with (1 1 1) surfaces. The studied molecular junctions at zero bias voltage are HOMO-based junctions and currents through these systems are driven by hole transport. The current–voltage characteristics of the both studied molecular junctions illustrate that negative differential resistance (NDR) feature is observed over the bias voltage of 2.0 V. Higher conductivity of fused furan dimmer and NDR character have been explained by the monitoring of the transmission resonance peak across the bias window against varying bias voltages.     

有机电双稳态器件

有机电双稳态器件(organic electrical bistability devices,OEBDs)具有低成本、易加工、小体积、快响应、低功耗和高存储密度等优点,在未来的信息存储和逻辑电路方面有着非常广阔的应用前景,正受到人们越来越多地的关注。但是有机电双稳态器件的工作原理还没有得到很好地理解,并且工作过程中所涉及的新概念、新理论等基本科学问题以及制备和加工过程中所涉及的新结构、新方法、新技术和新材料还有待进行深入地研究。本文综述了有机电双稳态器件近年来的研究进展,并探讨了它在电开关存储方面的应用前景以及需要解决的问题。     

双沟道实空间转移晶体管(RSTT)的研制

报道了在GaAs衬底上,采用δ掺杂GaAs/InGaAs双沟道结构,成功地研制出双沟道实空间转移晶体管(RSTT),它具有RSTT典型的"Λ"型负阻I-V特性和较宽的平坦谷值区。具体讨论了湿法腐蚀进行隔离台面,磁控溅射制作电极,快速热退火制作源漏低阻的欧姆接触等工艺步骤。器件的主要负阻参数PVCR可达10,对所研制的RSTT的负阻机制进行了初步探讨。