0.86μm激光扫描二维成像的实验研究

本文给出作者设计的0.86μm激光二维成像系统的原理框图、成像雷达距离方程和部分物体对0.86μm激光的反射对比度的测试数据,并展示了各类物体激光成像的照片.     

空冷型PEMFC电堆的单电池特性研究

本文对实验室自制的自增湿空冷型PEMFC电堆进行了自适应特性研究,并分析了各单电池的性能以及各电池的电压分布情况. 实验中设定操作条件为：阳极工作压力为2 bar,阴极风扇功率0.3 W,氢气室每隔10 s排水1 s. 从实验结果可以看出,空冷型PEMFC的电压分布与负载电流的大小具有一定的联系,大电流负载下电池的电压分布会出现明显的不均匀现象,根据分析结果可以看出,电堆的单体电压波动率与负载电流之间存在近似的指数关系分布,且各单片电池间内阻的差异与大电流下过高的电堆温度都会造成电压分布不均匀的现象.     

Numerical investigation on threading dislocation bending with InAs/GaAs quantum dots

The threading dislocations (TDs) in GaAs/Si epitaxial layers due to the lattice mismatch seriously degrade the performance of the lasers grown on silicon. The insertion of InAs quantum dots (QDs) acting as dislocation filters is a pretty good alternative to solving this problem. In this paper, a finite element method (FEM) is proposed to calculate the critical condition for InAs/GaAs QDs bending TDs into interfacial misfit dislocations (MDs). Making a comparison of elastic strain energy between the two isolated systems, a reasonable result is obtained. The effect of the cap layer thickness and the base width of QDs on TD bending are studied, and the results show that the bending area ratio of single QD (the bending area divided by the area of the QD base) is evidently affected by the two factors. Moreover, we present a method to evaluate the bending capability of single-layer QDs and multi-layer QDs. For the QD with 24-nm base width and 5-nm cap layer thickness, taking the QD density of 10¹¹ cm^-2 into account, the bending area ratio of single-layer QDs (the area of bending TD divided by the area of QD layer) is about 38.71%. With inserting five-layer InAs QDs, the TD density decreases by 91.35%. The results offer the guidelines for designing the QD dislocation filters and provide an important step towards realizing the photonic integration circuits on silicon.