GaAs Based InAs/GaSb Superlattice Short Wavelength Infrared Detectors Grown by Molecular Beam Epitaxy

InAs/GaSb superlattice （SL） short wavelength infrared photoconduction detectors are grown by molecular beam epitaxy on GaAs（O01） semi-insulating substrates. An interfacal misfit mode AISb quantum dot layer and a thick GaSb layer are grown as buffer layers. The detectors containing a 200-period 2 ML/S ML InAs/GaSb SL active layer are fabricated with a pixel area of 800×800 μm^2 without using passivation or antirefleetion coatings. Corresponding to the 50% cutoff wavelengths of 2.05μm at 77K and 2.25 μm at 300 K, the peak detectivities of the detectors are 4 × 10^9 cm·Hz^1/2/W at 77K and 2 × 10^8 cm·Hz1/2/W at 300K, respectively.     

Anisotropic Spin Splitting in Step Quantum Wells

By the method of finite difference, the anisotropic spin splitting of the AlxGa1-xAs/GaAs/Aly Ga1-yAs/AlxGal-xAs step quantum wells （QWs） are theoretically investigated considering the interplay of the bulk inversion asymmetry and structure inversion asymmetry induced by step quantum well structure and external electric field. We demonstrate that the anisotropy of the total spin splitting can be controlled by the shape of the QWs and the external electric field. The interface related Rashba effect plays an important effect on the anisotropic spin splitting by influencing the magnitude of the spin splitting and the direction of electron spin. The Rashba spin splitting presents in the step quantum wells due to the interface related Rashba effect even without external electric field or magnetic field.     

Effects of Different Plasma Energy Treatments on n-Type Al0.4Ga0.6N Material

El3ctronic properties, surface chemistry and surface morphology of plasma-treated n-Al0.4Ga0.6N material are studied by electrical contact measurements, atomic force microscopy and x-ray photoemission spectroscopy. Although excessive etching can cause the surface roughness to significantly increase, the nitrogen vacancies VN produced by the excessive etching can be compensated for by the negative effects of the rougher surface. Thus, VN produced by excessive etching plays a key role in Ohmic contact of high-A1 content AIGaN and it can reduce Ohmic contact resistance. The effect of rapid thermal annealing on the performance of n-Al0.4Ga0.6N can significantly reduce the etching damage caused by excessive etching.     

Phase-Transition and Magnetic Moment of the Gd3+ Ion in the Gd2Fe17 Compound

The structure and magnetic phase transitions of the Gd2Fe17 compound are investigated by using a differential thermal/thermogravimetric analyzer, x-ray diffraction, and magnetization measurements. The result shows that there are two phase structures for the Gd2Fe17 compound： the hexagonal Th2Nilr-type structure at high temperatures （above 1243℃）, and the rhombohedral Th2Zn17-type structure, respectively. A method to measure the magnetic moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound is presented. The moments of the Gd-sublattice and the Fe-sublattice in the Gd2Fe17 compound from 77 to 500 K are measured in this way with a vibrating sample magnetometer. A detailed discussion is presented.     

Simulation of Dual Frequency Capacitive Sheath over a Concave Electrode in Low Pressure

A self-consistent two-dimensional （2D） collisionless fluid model is developed to simulate the characteristics of a dual frequency capacitive sheath over an electrode with a cylindrical hole. The model consists of 2D time-dependent fluid equations coupled with Poisson＇s equation, in which the low-frequency （LF） and high-frequency current sources are applied to an electrode. Thus, the so-called equivalent circuit model coupling with the fluid equations will be able to self-consistently determine the relationship between the instantaneous voltage on the powered electrode and the sheath thickness. The time-averaged potential, electric field, ion density in the sheath and ion energy distributions at the bottom of the hole are calculated and compared for different LF frequencies. The results show that the LF frequency is crucial for determining the sheath structure. The existence of the cylindrical hole on the electrode obviously affects the sheath profile in the parallel to the electrode and makes the sheath profile tend to adapt the contours of the electrode, which is the plasma molding effect.     

化学发光酶免疫方法检测克伦特罗残留

建立了间接竞争化学发光酶免疫法(competitive indirect chemilumine scent enzyme immunoassy,ic-CLEIA)检测猪尿中残留克伦特罗(clenbuterol,CLB)的方法,并优化了竞争反应时间,Tween-20含量,PBS离子强度与pH4个参数。优化后的ic-CLEIA检出限可达0．01μg/L,检测范围为0．04～25．8μg/L,ED50为0．54μg/L;尿样检测的平均回收率为98％～120％,批内与批间相对标准偏差(variation of coefficent,CV)均小于10％。这些参数均优于目前广泛使用的ELISA方法,说明本CLEIA方法可替代ELISA法,用于实际尿样的检测。     

含铜MCM-48催化剂上糠醛选择性加氢制糠醇

 以MCM-48为载体,采用新颖的负载方法(有机官能团化法)制备了铜基负载型催化剂. 结果表明,活性组分以较高的负载量均匀地分散在载体MCM-48表面,且负载活性组分后,分子筛的结构未被明显破坏. 本文首次将采用此负载方法制备的铜基MCM-48催化剂用于糠醛选择性加氢制糠醇反应,并得到了较高的活性、稳定性及糠醇选择性,该催化剂可以与商业催化剂相比,具有潜在的工业应用价值. 与一维结构的MCM-41相比,三维孔道结构的MCM-48有效避免了孔堵塞,大大提高了催化剂的稳定性. 引入助剂镧有利于羰基加氢,明显提高了糠醛的转化率. 使用后的催化剂并未被氧化,催化剂失活的主要原因之一是积炭.     

焙烧温度对铁基催化剂催化浆态床F-T合成反应性能的影响

 采用连续共沉淀与喷雾干燥成型技术相结合的方法制备了微球形Fe-Cu-K-SiO2催化剂,并考察了焙烧温度对催化剂的结构和织构性质的影响. 结果表明,催化剂具有较好的织构和结构热稳定性,粘结剂SiO2起到了分散和稳定α-Fe2O3晶相的作用. 随着焙烧温度的升高,催化剂的比表面积逐渐减小,α-Fe2O3晶粒逐渐增大,催化剂体相中的Cu和K原子向表面富集,且Cu向表面的迁移更明显; 同时,催化剂中的α-Fe2O3和CuO相发生了一定程度的离析,Cu的助剂作用减弱,使催化剂在合成气气氛下难于还原碳化. 催化剂在n(H2)/n(CO)=0.67,GHSV=2.0 L/(g·h),p=1.5 MPa和θ=250 ℃下的浆态床F-T合成反应评价结果表明,升高焙烧温度,催化剂的初活性和最高活性下降,但运行稳定性提高,而且有效地抑制了CH4的生成,明显促进了烃产物向高碳数方向移动. 反应600 h后卸载下的催化剂的形貌观测表明,催化剂的磨损主要是由化学磨损引起的,提高焙烧温度可明显改善其抗磨损性能,焙烧温度高于400 ℃时,催化剂具有较好的抗磨损性能.     

ICP-AES法同时测定玻璃组份中的Ca、Mg、Ti、Fe、Pb、Cd、Al、Si、B、Zn、Cu元素

建立了一种用电感耦合等离子发射光谱(ICP-AES)法测定玻璃成份的简便、快速、准确、精密度好的方法．研究了样品的处理、标准样品的配制、谱线干扰等问题,并采用和基体匹配的方法消除基体的影响,进行了标准样品的分析、对照、精密度等试验,均取得了满意的结果．     

带弱"平台"皮秒光孤子的数值研究

通过数值求解变系数非线性薛定谔方程,发现光纤系统对带有弱“平台”的皮秒光孤子有独特的传输特性。在常参数光纤系统中,这种光孤子体现“呼吸”特性,而在特殊的分布参数光纤系统中,则能较平稳地传输。