金红石TiO_2中本征缺陷扩散性质的第一性原理计算

基于密度泛函理论的爬坡弹性带方法,对金红石相二氧化钛晶体中钛间隙、钛空位、氧间隙、氧空位4种本征缺陷的扩散特征进行了研究.对比4种本征缺陷在晶格内部沿不同扩散路径的过渡态势垒后发现,缺陷扩散过程呈现出明显的各向异性.其中,钛间隙和氧间隙沿[001]方向具有最小的扩散势垒路径,激活能分别为0.505 eV和0.859 eV;氧空位和钛空位的势垒最小的扩散路径分别沿[110]方向和[111]方向,激活能分别为0.735 eV和2.375 eV.     

带有n+深阱的三阱CMOS工艺中寄生NPN双极效应及其对电荷共享的影响

基于三维TCAD器件模拟, 研究了带有 n⁺深阱的90 nm三阱CMOS器件在重离子辐照下产生的电荷共享效应. 研究结果表明在重离子辐照时, n⁺深阱会导致寄生的NPN双极型晶体管触发, 显著增强NMOS间的电荷共享, 其放大因子达到双阱工艺中寄生PNP晶体管放大因子的2---4倍. 进而分别研究了n阱接触和p 阱接触对寄生NPN双极放大的影响, 结果表明增大p阱接触的面积和减小 n 阱接触的距离将抑制NPN晶体管的放大作用, 而增大n 阱接触的面积将增强NPN的放大作用.     

Mechanism of single-event transient pulse quenching between dummy gate isolated logic nodes

As integrated circuits scale down in size,a single high-energy ion strike often affects multiple adjacent logic nodes.The so-called single-event transient(SET)pulse quenching induced by single-event charge sharing collection has been widely studied.In this paper,SET pulse quenching enhancement is found in dummy gate isolated adjacent logic nodes compared with that isolated by the common shallow trench isolation(STI).The physical mechanism is studied in depth and this isolation technique is explored for SET mitigation in combinational standard cells.Three-dimensional(3D)technology computer-aided design simulation(TCAD)results show that this technique can achieve efficient SET mitigation.     

Dependence of switching process on the perpendicular magnetic anisotropy constant in P-MTJ

We investigate the dependence of the switching process on the perpendicular magnetic anisotropy(PMA) constant in perpendicular spin transfer torque magnetic tunnel junctions(P-MTJs) using micromagnetic simulations. It is found that the final stable states of the magnetization distribution of the free layer after switching can be divided into three different states based on different PMA constants: vortex, uniform, and steady. Different magnetic states can be attributed to a trade-off among demagnetization, exchange, and PMA energies. The generation of the vortex state is also related to the non-uniform stray field from the polarizer, and the final stable magnetization is sensitive to the PMA constant. The vortex and uniform states have different switching processes, and the switching time of the vortex state is longer than that of the uniform state due to hindrance by the vortex.     

基于梯度掺杂策略的碳纳米管场效应管性能优化

双极性传输特性是制约碳纳米管场效应管(carbon nanotube field effect transistors,CNFETs)性能提高的一个重要因素.为降低器件的双极性传输特性并获得较大的开关电流比,提出了一种漏端梯度掺杂策略,该策略不仅适合于类MOS碳纳米管场效应管(C-CNFETs),同时也适合于隧穿碳纳米管场效应管(T-CNFETs).基于非平衡格林函数的数值研究结果表明,该策略不仅能有效降低器件的双极传输特性,而且能将器件开关电流比提高数个数量级.进一步研究发现,该掺杂策略在这两类碳纳米管 关键词： 梯度掺杂 带间隧穿 双极性传输 碳纳米管场效应管     

p型金属氧化物半导体场效应晶体管界面态的积累对单粒子电荷共享收集的影响

由于负偏置温度不稳定性和热载流子注入,p型金属氧化物半导体场效应晶体管(pMOSFET)将在工作中不断退化,而其SiO₂/Si界面处界面态的积累是导致其退化的主要原因之一. 采用三维器件数值模拟方法,基于130 nm体硅工艺,研究了界面态的积累对相邻pMOSFET之间单粒子电荷共享收集的影响. 研究发现,随着pMOSFET SiO₂/Si界面处界面态的积累,相邻pMOSFET漏端的单粒子电荷共享收集量均减少. 还研究了界面态的积累对相邻反相器中单粒子电荷共享收集 关键词： 负偏置温度不稳定性 电荷共享收集 双极放大效应 单粒子多瞬态     

Suppressing the hot carrier injection degradation rate in total ionizing dose effect hardened nMOSFETs

Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose (TID) effect. However, their capability of resisting the hot carrier effect (HCE) has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers (the annular source nMOSFETs) are also studied to provide a possible alternative for the designers.