Identity of defect causing nonideality in nearly ideal Au/n-Si Schottky barriers

We have proposed a mechanism of nonideality, i.e., the temperature dependence of the ideality factor, in nearly ideal Au/n-Si Schottky barriers. Because of the nature of metal-induced gap states, positively ionized defects close to the interface are considered to cause local lowering of the Schottky barrier height (SBH) due to downward bending of the energy band. These positively charged defects become neutralized in equilibrium with the Fermi level due to the band bending, when they are very close to the interface. However, because the SBH lowering disappears by the neutralization of donor, the energy level of donor with a usual energy level scheme rises above the Fermi level after the neutralization. This contradiction to the equilibrium neutralization is resolved by Si self-interstitial with a large negative-U property, which is generated by the fabrication process. The energy level of the donor estimated from the SBH lowering is in good agreement with that of theoretical calculation of Si self-interstitial. Thus, the defect is concluded to be the Si self-interstitial, which is distributed to more than 10 Å depth from the interface.     

Rheological Technique as a Sensitive Method to Characterize the Chain Diffusion across the Interface between Polystyrene and Carbon Black Filled Polystyrene

The mutual diffusion process and interphase development taking place at the interface between disks of polystyrene (PS) and carbon black filled polystyrene (CB-PS) in the molten state were investigated by a small-amplitude, oscillatory shear, rheological technique. The rheological method was employed to probe the thermorheological complexity of these polymer disks. It was found that the dynamic complex shear modulus, G*(t), increased with the time of contact in two time regimes at a fixed frequency. The time of transition between the two regimes was observed to be close to the time needed for the transition from the Rouse mode to the reptation mode. The results showed that the content of the carbon black and the temperature affected the slope of the G*(t) – t curve. Scanning electron microscopy revealed the interface disappeared when the diffusion process was complete.     

Study on the recovery of NBTI of ultra-deep sub-micro MOSFETs

Taking the actual operating condition of complementary metal oxide semiconductor (CMOS) circuit into account, conventional direct current (DC) stress study on negative bias temperature instability (NBTI) neglects the detrapping of oxide positive charges and the recovery of interface states under the `low' state of p-channel metal oxide semiconductor field effect transistors (MOSFETs) inverter operation. In this paper we have studied the degradation and recovery of NBTI under alternating stress, and presented a possible recovery mechanism. The three stages of recovery mechanism under positive bias are fast recovery, slow recovery and recovery saturation.     

单分子器件与电极间耦合界面对电子传输的影响

利用自恰tight-binding 理论，对由phenalenyl分子构成的全对称三电极纳米单分子器件的电子传导特性进行了理论研究. 通过改变电极与分子界面上的耦合，得出了分子与原子线电极间耦合强度变化对电子传输的影响. 结果显示电子通过phenalenyl分子器件的概率随着分子与电极的耦合强度变弱而减小. 当耦合强度变大时，不仅电子通过phenalenyl分子器件的概率变大，而且在较宽的能带内电子都可以通过phenalenyl分子. 所得结果还揭示出在特定的能区，对称三电极phenalenyl分子可以构成一个无源正负能量开关器件的新特性.     

Ultra fine carbon nitride nanocrystals synthesized by laser ablation in liquid solution

Crystalline carbon nitride nanopowders and nanorods have been successfully synthesized at room temperature and pressure using the novel technique of pulsed laser ablation of a graphite target in liquid ammonia solution. High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and Fourier transform infrared spectroscopy (FTIR) were used to systematically study the morphology, nanostructure and chemical bonding. The experimental composition and structure of the nanoparticles are consistent with the theoretical calculations for α-C₃N₄. After 2 h ablation the particles had a size distribution ∼8–12 nm, whereas after 5 h ablation the particles had grown into nanorod-like structures with a crystalline C₃N₄ tip. A formation mechanism for these nanorods is proposed whereby nanoparticles are first synthesized via rapid formation of an embryonic particle, followed by a slow growth, eventually leading to a one-dimensional nanorod structure.     

用PC机代替打点计时器计时

在匀变速直线运动的实验中，利用PC机的串行接口来记录运动小车通过测量点的时刻值，以此代替打点计时器计时。     

三维双气泡融合的格子Boltzmann模拟

针对基于自由能模型的格子Boltzmann方法,推导D3Q15格子模型对应的平衡态分布函数;采用该模型模拟双气泡的融合过程.结果表明,气泡的融合不仅与它们之间的初始间距有关,还与表面张力有关.表面张力越大,气泡融合的临界距离也越大.此外,研究气泡融合速度与初始间距、表面张力及粘性系数的关系.     

Ionic diffusion on a lattice: Effects of the order-disorder transition on the dynamics of non-equilibrium systems

We examine the behaviour of the concentration profiles of particles with repulsive interactions diffusing on a host lattice. At low temperature, the diffusion process is strongly influenced by the presence of ordered domains. We use mean field equations and Monte-Carlo simulations to describe the various effects which influence the kinetic behaviour. An effective diffusion coefficient is determined analytically and is compared with the simulations. Finite gradient effects on the ordered domains and on the diffusion are discussed. The kinetics studied is relevant for superionic conductors, for intercalation and also for the diffusion of particles adsorbed on a substrate. Received: 26 June 1997 / Revised: 18 September 1997 / Accepted: 10 November 1997     

间断问题的并行多重网格预条件共轭梯度法求解

首先比较了四种串行多重网格预条件共轭梯度法求解四类典型间断问题时,数值收敛因子与间断类型、间断程度、网格步长的关系;然后,在算法中引入Schwarz并行,探讨了并行算法收敛因子与子区域个数的关系,以及Schwarz并行的获益。给出了详细的性能比较结果。