Electrical Characterization of Metal-Insulator-Metal Capacitors with Atomic-Layer-Deposited HfO2 Dielectrics for Radio Frequency Integrated Circuit Application

Metal-insulator-metal （MIM） capacitors with atomic-layer-deposited HfO2 dielectric and TaN electrodes are investigated for rf integrated circuit applications. For 12nm HfO2, the fabricated capacitor exhibits a high capacitance density of 15.5fF/μm2 at 100kHz, a small leakage current density of 6.4 × 10^-9 A/cm^2 at 1.8V and 125℃, a breakdown electric field of 2.6 MV//cm as well as voltage coefficients of capacitance （VCCs） of 2110ppm/V^2 and -824 ppm/V at 100kHz. Further, it is deduced that the conduction mechanism in the high field range is dominated by the Poole-Frenkel emission, and the conduction mechanism in the low field range is possibly related to trap-assisted tunnelling. Finally, comparison of various HfO2 MIM capacitors is present, suggesting that the present MIM capacitor is a promising candidate for future rf integrated circuit application.     

MOVPE生长GaN的表面反应机理

利用量子化学的 DFT 理论,对 MOVPE 生长 GaN 薄膜的表面初始反应机理进行研究。通过计算GaCH3和NH3在GaN(0001)-Ga面的4种吸附位的能量曲线发现,GaCH3在各吸附位的吸附能差值不大,因此容易在表面迁移;而NH3在各吸附位的吸附能差值较大,最稳定吸附位为Top位,迁移到其他位置需要克服较大能垒。在此基础上,提出了以NH3和 GaCH3为表面生长基元,在GaN(0001)-Ga面连续生长,最终形成环状核心的二维生长机理：在环状核心形成过程中,第1个GaN核生长需要3个NH3和1个GaCH3,可表示为Ga( NH2)3。第2个GaN核生长可利用已有的1个N作为配位原子,故只需2个NH3和1个GaCH3。2个GaN核可表示为( NH2)2 Ga-NH-Ga( NH2)2。第3个GaN核生长可利用已有的2个N作为配位原子,故只需要1个NH3和1个GaCH3。3个GaN核构成环状核心,可表示为Ga3( NH)3( NH2)3。后续的生长将重复第2个核和第3个核的生长过程,从而实现GaN薄膜的连续台阶生长。     

Nonclassical state via superposition of two coherent states (π/2 out of phase) and related entangled states

Nonclassical features of the superposition of two coherent states which are π/2 out of phase are discussed, such as sub-Poissonian photon statistics and quadrature squeezing, as well as negativity of the Wigner function. Special nonclassicality is found in the special state where the relative phase of superposition has relationship with the average photon number. The analysis of the amount of entanglement is also presented for the related two-mode entangled coherent states.     

负折射率材料对产生Casimir排斥力的影响

研究了负折射率材料对产生Casimir排斥效应的影响. 两材料板间的Casimir排斥力的发生取决于两板以及其间媒质的电磁特性,通过理论与数值结果的分析研究给出电磁特性所影响排斥力的产生趋势. 对于由Drude-Lorentz型色散关系描述等效介电常数和磁导率的负折射率材料,调节各特征频率参数可实现Casimir排斥效应. 关键词： Casimir排斥力 负折射率材料 Drude-Lorentz型色散关系     

双脉冲高功率脉冲调制器的设计

采用螺旋线和折叠线技术相结合的方法,设计了一种基于水介质高功率脉冲调制器。该调制器采用了两个开关,通过控制两个开关的导通时刻,可以在两个负载上得到脉冲长度相等的两个脉冲。对该种折叠型传输线的波过程进行了详细分析,给出了过渡段部分阻抗等参数对负载电压的影响;用Pspice电路软件对脉冲形成线的充电电压和二极管电压、电流进行了模拟;最后利用高压同轴电缆,对该种类型调制器进行了低压情况下的验证实验,实验结果与理论分析、模拟研究一致。此种类型的调制器具有结构紧凑、可同时输出两个脉冲的优点。     

Reconstruction of band-limited signals from multichannel and periodic nonuniform samples in the linear canonical transform domain

Linear canonical transforms (LCTs) are a family of integral transforms with wide application in optical, acoustical, electromagnetic, and other wave propagation problems. This paper addresses the problem of signal reconstruction from multichannel and periodic nonuniform samples in the LCT domain. Firstly, the multichannel sampling theorem (MST) for band-limited signals with the LCT is proposed based on multichannel system equations, which is the generalization of the well-known sampling theorem for the LCT. We consider the problem of reconstructing the signal from its samples which are acquired using a multichannel sampling scheme. For this purpose, we propose two alternatives. The first scheme is based on the conventional Fourier series and inverse LCT operation. The second is based on the conventional Fourier series and inverse Fourier transform (FT) operation. Moreover, the classical Papoulis MST in FT domain is shown to be special case of the achieved results. Since the periodic nonuniformly sampled signal in the LCT has valuable applications, the reconstruction expression for the periodic nonuniformly sampled signal has been then obtained by using the derived MST and the specific space-shifting property of the LCT. Last, the potential applications of the MST are presented to show the advantage of the theory.     

Exotic entanglement scaling of Heisenberg antiferromagnet on honeycomb lattice

The scaling behaviors of entanglement entropy (EE) against dimension cut-off of density matrix renormalization group (DMRG) in an anisotropic Heisenberg model on honeycomb lattice are investigated. In the gapped dimer phase, the entanglement spectrum (ES) exhibits large gaps and the EE shows an unexpected linear scaling before convergence. In contrast in the gapless Néel phase, the ES decays in a much smoother way, and the EE scales logarithmically. Our calculations show that the linear scaling in the dimer phase originates from one dominant Schmidt number plus n (nearly) degenerate Schmidt numbers that are much smaller than the dominant one. The non-trivial entanglement-scaling properties of the dimer and Néel phases could potentially be used for their detections.     

Finite-time disturbance observer-based trajectory tracking control for quadrotor unmanned aerial vehicle with obstacle avoidance

This paper investigates the problem of trajectory tracking control for quadrotor unmanned aerial vehicle (UAV) in the presence of dynamic obstacles and external disturbance forces/torques. More specifically, two new sliding mode disturbance observers are firstly designed to estimate the external disturbances, in which the observation errors can converge to zero in finite time. Furthermore, utilizing the observation information, a new sliding mode surface-like variable-based position tracking control scheme and a novel nonsingular terminal sliding mode-based attitude synchronization control scheme are developed to drive the UAV tracking the reference trajectory with obstacle avoiding. Moreover, the tracking errors of the close-loop control system can converge to zero within finite time by the analyses of Lyapunov methodology. Finally, the numerical simulation results are presented to illustrate the effectiveness of the proposed control schemes.     

The Soft Point and Its Applications in Body Falling*

From the mesoscopic point of view, a definition of soft point is introduced by considering the attributes of geometric profile and mass distribution. After that, this concept is used to develop the soft matching technique to simulate the chaotic behaviors of the equations. Especially, a tennis model with deformation factor a(t) is proposed to derive a generalized Newton-Stokes equation v′(t) = λ(v T-a(t)v(t)). Furthermore, a concept of duality of deformation factor a(t) and velocity v(t) with re...     

Cobimetinib 消旋体的合成

以3-羟基氮杂环丁烷盐酸盐为原料,经Cbz保护和氧化反应制得1 苄氧羰基氮杂环丁烷-3-酮(3); 3与N-亚硝基哌啶发生亲核反应后与2,3-二氟-(2-氟-4-碘氨基）苯甲酸发生缩合反应,最后经氯化氢脱亚硝基和碱化合成了Cobimetinib消旋体,其结构经¹H NMR和HR-MS（ESI）确证。