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101.
A. Kussmaul S. Vernon P. C. Colter R. Sudharsanan A. Mastrovito K. J. Linden N. H. Karam N. H. Karam S. C. Warnick M. A. Dahleh 《Journal of Electronic Materials》1997,26(10):1145-1153
We have used spectroscopic ellipsometry to perform real-time monitoring during metalorganic chemical vapor deposition growth
of AlGaAs (on GaAs) and InGaAs (on GaAs and InP). Optical constants for these materials were obtained up to growth temperatures
of 600 to 700°C. This information permits real-time extraction of composition and layer thickness from the raw ellipsometric
data at sample rates on the order of 0.5 Hz. We describe closed-loop control of composition and total layer thickness on AlGaAs-based
structures, including Bragg reflectors. In-situ data obtained on double-heterostructure quantum-well laser structures demonstrate that spectroscopic ellipsometry is an extremely
powerful monitoring and quality-control tool, giving important real-time information on complex structures that would be difficult
and time-consuming to obtain after growth. 相似文献
102.
103.
用50W连续波CO_2激光器为热源,诱发SiH_4和C_2H_4反应,合成SiC超细粉末。实验确定了反应腔体内压力p、气源中的C/Si原子比、喷嘴内径2r以及激光功率密度与粉末特性之间的关系,并对合成的产物进行物理、化学表征。 相似文献
104.
连续时间广义边值系统被描述为Ex(t)=Ax(t)+Bu(t),V0x(0)+Vrx(T)=v,其中E是奇异方阵,u(t)满足任意次可微,本文讨论了一类连续时间广义边值系统的有关向内和向外边值过程的两个重要概念,并在此基础上给出了能控性和能观性定义和判别准则. 相似文献
105.
M. R. Islam R. V. Chelakaea J. G. Neff K. G. Fertitta P. A. Grudowski A. L. Holmes F. J. Ciuba R. D. Dupuis J. E. Fouquet 《Journal of Electronic Materials》1995,24(6):787-792
AlGaAs double heterostructures are grown by low-pressure metalorganic chemical vapor deposition to evaluate the level of oxygen
contamination in different trimethylaluminum sources. Effects of arsine purifiers, misoriented substrates, atmospheric exposure
of the growth chamber, and possible phosphorus contamination are also studied. Extensive characterization is performed on
these films by a variety of methods, including high-resolution x-ray diffraction, photoluminescence (PL), time-resolved photoluminescence,
and secondary-ion mass spectrometry. The PL intensities for structures grown with the low-alkoxide grade are reproducibly
much greater than those grown with the regular-grade TMA1. The use of AsH3 purification improves the PL intensity. 相似文献
106.
化工工艺计算机辅助设计 总被引:1,自引:0,他引:1
本文根据化工工艺设计的特点,阐述了化工工艺设计与CAD的关系和开发研制计算机辅助化工工艺设计软件的思想,即将工艺设计、工艺图绘制与相关数据处理融为一体,并遵循这一构思,提出了软件开发研制的方法。 相似文献
107.
108.
Low-loaded vanadia-titania catalysts have been prepared by impregnation of titania P-25 (Degussa). The catalysts were characterized by X-ray diffraction, specific surface area and porosity assessment by nitrogen adsorption at 77 K. For very low vanadia contents the absence of surface acid Brønsted sites leads to dimerization on surface acid Lewis sites, whereas the presence of surface acid Bransted sites when the vanadia content is increased leads to oxidation to carbonyl and carboxylate species. 相似文献
109.
It is shown that steady-state kinetic data do not allow the discrimination between the redox and associated mechanisms of the partial oxidation reactions. A discrimination between these mechanisms was performed using transient experiments. The obtained rate expressions are in agreement with experimental kinetic data for catalytic partial oxidation of o-xylene.
An influence of the conjugate oxidation of a catalyst surface on dynamics and kinetics of the heterogeneous catalytic oxidative reactions is considered. Computing simulation of methane oxidative coupling of methane reaction at lowered temperature and elevated pressure has been performed. It showed that the reaction order with respect to oxygen exceeding unity is consistent with the chain branching mechanism of the reaction in the presence of TiSi2 and TiB2 and showed the important role of the branching chain cycles in the low-temperature OCM reaction at elevated pressure. 相似文献
110.
The paper describes the integration of a chemical and a vapour-compression heat pump for energy storage applications. The vapour-compression system is designed to operate using the UK cheap rate ‘Economy 7’ electricity tariff. The system is characterized thermodynamically using various refrigerant/absorbent pairs in the chemical storage circuit and an ozone-friendly refrigerant, R134a, in the vapour-compression circuit. Results indicate that the H2O/Na2S pair provides a high energy storage density and is the most suitable for use in this system. The paper also describes the design features of a domestic-sized version of this heat pump system. Air in the sunspace (conservatory) of a house was used as a heat source for the heat pump. 相似文献