Optimization of Metamorphic InGaAs Quantum Wells on GaAs Grown by Molecular Beam Epitaxy

We investigate the molecular beam epitaxy growth of metamorphic InxGal-xAs materials （x up to 0.5） on GaAs substrates systematically. Optimization of structure design and growth parameters is aimed at obtaining smooth surface and high optical qualdty. The optimized structures have an average surface roughness of 0.9-1.8 nm. It is also proven by PL measurements that the optical properties of high indium content （55%） InGaAs quantum wells are improved apparently by defect reduction technique and by introducing Sb as a surfactant. These provide us new ways for growing device quality metamorphic structures on GaAs substrates with long-wavelength emissions.     

Optical Properties of Highly Strained GaInAs／GaAs Quantum Wells Grown by Sb Assistance

Optical properties of highly strained GaInAs/GaAs quantum wells (QWs) grown by molecular beam epitaxy with Sb assistance are investigated. The samples grown by Sb incorporation and Sb pre-deposition methods display high room-temperature photoluminescence (PL) intensity at extended 10ng wavelength. This result is explained by the surfactant effects of Sb during the growth of GaInAs/GaAs QW systems. An abnormal Sshaped temperature dependence of the PL peak position is found in the In0.42Ga0.58As/GaAs triple QWs sample grown with Sb pre-deposition. By investigating the transmission electron microscope images and time-resolved PL spectra, it is found that the S-shaped temperature dependence of the PL peak position originates from the exciton 10calization effect brought by the Sb-rich clusters on the QW interface.     

1.3μm自组织InGaAs/InAs/GaAs量子点激光器分子束外延生长

报道了分子束外延生长的1.3μm多层InGaAs/InAs/GaAs自组织量子点及其室温连续激射激光器.室温带边发射峰的半高宽小于35meV,表明量子点大小比较均匀.原子力显微镜图像显示,量子点密度可以控制在(1～7)×1010cm-2范围之内,而面密度处于4×1010cm-2时有良好的光致发光谱性能.含有三到五层1. 3μm量子点的激光器成功实现了室温连续激射.     

1.3μm自组织InGaAs/InAs/GaAs量子点激光器分子束外延生长

报道了分子束外延生长的1.3μm多层InGaAs/InAs/GaAs自组织量子点及其室温连续激射激光器.室温带边发射峰的半高宽小于35meV,表明量子点大小比较均匀.原子力显微镜图像显示,量子点密度可以控制在(1～7)×1010cm-2范围之内,而面密度处于4×1010cm-2时有良好的光致发光谱性能.含有三到五层1. 3μm量子点的激光器成功实现了室温连续激射.     

Wet etching and passivation of GaSb-based very long wavelength infrared detectors

The etching and passivation processes of very long wavelength infrared (VLWIR) detector based on the InAs/GaSb/AlSb type-II superlattice have been studied. By studying the effect of each component in the citric acid solution (citric acid, phosphoric acid, hydrogen peroxide, deionized water), the best solution ratio is obtained. After comparing different passivation materials such as sulfide + SiO₂, Al₂O₃, Si₃N₄ and SU8, it is found that SU8 passivation can reduce the dark current of the device to a greater degree. Combining this wet etching and SU8 passivation, the R₀A of VLWIR detector with a mesa diameter of 500 μm is about 3.6 Ω ·cm² at 77 K.     

Influence of Growth Parameters of Frequency-Radio Plasma Nitrogen Source on Extending Emission Wavelengths from 1.31 μm to 1.55 μm GaInNAs/GaAs Quantum Wells Grown by Molecular-Beam Epitaxy

High （42.5%） indium content GaInNAs/GaAs quantum wells with room temperature emission wavelength from 1.3μm to 1.5μm range were successfully grown by Radio Frequency Plasma Nitrogen source assisted Molecular Beam Epitaxy, The growth parameters of plasma power and N2 flow rate were optimized systematically to improve the material quality. Photoluminescence and transmission electron microscopy measurements showed that the optical and crystal quality of the 1.54μm GaInNAs/GaAs QWs was kept as comparable as that in 1.31 μm.     

城市环境治理中智慧环保系统的应用研究

对城市环境治理而言，智慧环保系统即利用物联网来动态监测城市环境情况的在线系统。通过该系统可以对水体、大气和各种声光污染进行有效监控，从而提升城市环境治理工作的效率。对城市环境治理中应用智慧环保系统的情况进行分析，并提出若干方案来提升应用效果，比如说建立分布式的环境传感器系统，监控预警平台与环境举报系统、环境控制与处置中心、在线事务办理平台等，为今后更好地利用智慧环保系统提升城市环境质量提供保障。     

膜供氧催化氧化处理太空舱冷凝废水研究

采用膜供氧催化氧化反应器处理太空舱冷凝废水。以乙醇为目标污染物,研究了膜供氧催化氧化反应器对其的处理效果,并考察了催化反应对膜传质模型的影响。结果表明,随着停留时间的增加,乙醇的去除率增大,中间产物乙酸的生成率减少。当废水流量为0.5mL·min-1,气室压力为2kPa时,乙醇的去除率可达86.1%,其中81.4%完全氧化,4.7%转化成乙酸。基于传质模型对实验结果分析表明,催化反应有利于提高膜供氧总传质系数,当流量为0.5mL·min-1时,与无催化反应条件相比,氧总传质系数提高11.8倍。停留时间的增加也有利于提高膜供氧传质系数。结果表明,膜供氧催化氧化反应器可高效降解冷凝废水中的乙醇,在太空舱冷凝废水处理中有潜在的应用价值。     

Metamorphic InGaAs Quantum Well Laser Diodes at 1.5μm on GaAs Grown by Molecular Beam Epitaxy

We report a 1.5-μm InGaAs/GaAs quantum well laser diode grown by molecular beam epitaxy on InGaAs metamorphic buffers. At 150K, for a 1500×10μm^2 ridge waveguide laser, the lazing wavelength is centred at 1.508 μm and the threshold current density is 667 A/cm^2 under pulsed operation. The pulsed lasers can operate up to 286 K.