Electronic Energy Levels in an Asymmetric Quantum-Dots-in-a-Well Structure for Infrared Photodetectors

Theoretical calculation of electronic energy levels of an asymmetric InAs/InGaAs/GaAs quantum-dots-in-a-well （DWELL） structure for infrared photodetectors is performed in the framework of effective-mass envelope-function theory. Our calculated results show that the electronic energy levels in quantum dots （QDs） increase when the asymmetry increases and the ground state energy increases faster than the excited state energies. Furthermore, the results also show that the electronic energy levels in Q Ds decrease as the size of QDs and the width of quantum well （QW） in the asymmetric DWELL structure increase. Additionally, the effects of asymmetry, the size of QDs and the width of QW on the response peak of asymmetry DWELL photodetectors are also discussed.     

Temperature Insensitivity of Optical Properties of InAs/GaAs Quantum Dots due to a Pregrown InGaAs Quantum Well

Both the peak position and linewidth in the photoluminescence spectrum of the InAs/GaAs quantum dots usually vary in an anomalous way with increasing temperature. Such anomalous optical behaviour is eliminated by inserting an In0.2Ga0.8As quantum well below the quantum dot layer in molecular beam epitaxy. The insensitivity of the photoluminescence spectra to temperature is explained in terms of the effective carrier redistribution between quantum dots through the In0.2Ga0.8As quantum well.     

初中物理实验综合评价的实践与思考

对现行的初中物理实验综合评价的现状进行了理性的反思. 同时尝试对考试方式、 内容及手段作出调 整和改进, 并对今后的初中物理实验综合评价提出一些建议     

易水解聚酯的合成及其水解性能

作者合成了一种可纺性易水解聚酯,由于其可与其他熔纺高聚物进行复合或共混纺丝,制成海岛型纤维,这种海岛型纤维只要经过热（碱）水处理,就能形成微细纤维,使该聚合物有着非常广泛的应用前景［１］．本文主要讨论这种可成纤易水解聚酯的合成及其水解性能．１原料对苯...     

例谈摩擦力计算中容易忽视的问题

在计算摩擦力的教学中,对物体做受力分析时,常涉及到有多个弹力N,由于学生对f=uN公式中摩擦力f与弹力N关系的不够理解,因而容易忽略f与N之间的内在联系．下面通过实例来谈谈摩擦力计算中的此类问题．