Monte Carlo simulation of in-plane spin-polarized transport in GaAs/GaAlAs quantum well in the three-subband approximation

We develop a Monte Carlo (MC) tool incorporated with the three-subband approximation model to investigate the in-plane spin-polarized transport in GaAs/GaAlAs quantum well. Using the tool, the effects of the electron occupation of higher subbands and the intersubband scattering on the spin dephasing have been studied. Compared with the corresponding results of the simple one-subband approximation model, the spin dephasing length is reduced four times under 0.125\,kV/cm of driving electric field at 300K by the MC tool incorporated with the three-subband approximation model, indicating that the three-subband approximation model predicts significantly shorter spin dephasing length with temperature increasing. Our simulation results suggest that the effects of the electron occupation of higher subbands and the intersubband scattering on the spin-dependent transport of GaAs 2-dimensional electron gas need to be considered when the driving electric field exceeds the moderate value and the lattice temperature is above 100K. The simulation by using the MC tool incorporated with the three-subband approximation model also indicates that, under a certain driving electric field and lattice temperature, larger channel widths cause spins to be depolarized faster. Ranges of the three components of the spins are different for three different injected spin polarizations due to the anisotropy of spin--orbit interaction.     

相干信号源的空时三维参数分离估计方法

文中提出了一种宽频段窄带相干信号源的频率和二维波达方向估计的新方法。该方法利用L型阵列并结合一定的时域信息,将相干源的三维参数估计问题转化为3个一维问题,并在每一维使用空间平滑方法和ESPR IT算法求解相应参数,最后通过求解联立方程,获得相干信号的三维参数。因此,避免了谱峰搜索,并且算法本身的并行处理能力,提高了测向系统的实时性。计算机仿真结果表明了该算法的有效性。     

PTCR陶瓷化学沉积镍电极界面结构及特性的研究

通过伏安特性和阻温特性测试研究了不同沉积条件下所得化学沉积镍电极BaTiO3基半导瓷热敏电阻元件的电性能，利用扫描电镜、透射电镜和X—衍射等现代分析手段，重点分析了在不同工艺条件下得到的化学镀镍电极与PTCR陶瓷之间的纳米界面结构及其特性，得到良好的欧姆接触化学镀镍电极的实验参数。