InGaAsP/InP有源时分光子交换器件

自行设计并研制成功了两种有源时分光子交换器件：ＩｎＧａＡｓＰ／ＩｎＰ ＥＭＰＢＨ双稳激光器ＩｎＧａＡｓＰ／ＩｎＰ ＭＱＷ ＤＣＰＢＨ双稳激光器，对这两种器件的部分性能作了简要报道。     

InGaAs/InP中离子注入和新型HPT

ＩｎＧａＡｓ／ＩｎＰ是制作光电器件与微波器件的重要材料。离子注入ＩｎＧａＡｓ／ＩｎＰ做掺杂或制作高阻层是人们十分关注的研究课题。采用Ｆｅ＾＋注入ＩｎＧａＡｓ／ＩｎＰ得到了电阻率升高的好结果。用Ｂｅ＾＋注入制作了新结构ＨＰＴ的基区。研制成功了在１．５５μｍ波长工作的ＩｎＧａＡｓ／ＩｎＰ新结构光电晶体管,在０．３μＷ入射光条件下,光电增益为３５０。     

张应变GaAs层引入使InAs/InP量子点有序化排列的机理研究

采用ＬＰ－ＭＯＶＰＥ技术,在（００１）ＩｎＰ衬底上生长的ＩｎＡｓ／ＩｎＰ自组装量子点是无序的。为了解决这个问题,在ＩｎＰ衬底上先生长张应变的ＧａＡｓ层,然后再生长ＩｎＡｓ层,可得到有序化排列的量子点。本文对张应变ＧａＡｓ层引入使量子点有序化排列的机理进行了分析,为生长有序化、高密度,均匀性好自组装量子点提供了依据。     

1.3μmInGaAsP／InP增益耦合型分布反馈激光器

采用两次液相外延技术制备了１．３μｍＩｎＧａＡｓＰ／ＩｎＰ内含吸收光栅的增益耦合型分布反馈激光器，成功地利用湿法腐蚀光栅技术，控制吸收光栅的形状和占空比，实现了增益耦合型ＤＦＢ激光器在室温下的脉冲激射，器件表现出了ＤＦＢ模式的单模工作特性。     

n型GaSb,InGaAsSb的MBE生长和特性研究

本文报导了非故意掺杂ＩｎＧａＡｓＳｂ本底浓度的降低和掺Ｔｅｎ型ＧａＳｂ和ＩｎＧａＡｓＳｂ的ＭＢＥ生长与特性的研究结果。结果表明，通过生长工艺的优化，ＧａＳｂ和ＩｎＧａＡｓＳｂ的背景空穴浓度可分别降至１．１×１０~（１６）ｃｍ~（－３）和４×１０~（１６）ｃｍ~（－３），室温空穴迁移率分别为９４０ｃｍ２／ｖ．ｓ和２６０ｃｍ~２／ｖ．ｓ。用Ｔｅ作ｎ型掺杂剂，可获得载流子浓度在１０~（１６）～１０~（１８）ｃｍ~（－３）的优质ＧａＳｂ和ＩｎＧａＡｓＳｂ外延层，所研制的材料已成功地制备出Ｄ_λ~＊＝４×１０~（１０）ｃｍＨｚ~（１／２）／Ｗ的室温ＩｎＧａＡｓＳｂ红外探测器和室温脉冲ＡｌＧａＡｓＳｂ／ＩｎＧａＡｓＳｂ双异质结激光器。     

国产金属有机化合物TMGa,TMAl,TMIn和TMSb的MOVPE鉴定

利用我们研制的常压ＭＯＶＰＥ设备对国产ＴＭＧａ、ＴＭＡｌ、ＴＭＩｎ和ＴＭＳｂ进行了鉴定，为此分别生长了ＧａＡｓ、ＡｌＧａＡｓ、ＩｎＰ、ＧａＳｂ外延层和ＧａＡｓ／ＡｌＡｓ、ＧａＳｂ／ＩｎＧａＳｂ超晶格和ＧａＡｓ／ＡｌＧａＡｓ量子阱结构。表征材料纯度的７７Ｋ载流予迁移率分别达到ＧａＡｓ：μ＿ｎ＝５６６００ｃｍ￣２／Ｖ·ｓ，Ａｌ＿（０．２５）Ｇａ＿（０．７５）Ａｓ：μ＿ｎ＝５１６０ｃｍ￣２／Ｖ·ｓ，ＩｎＰ：μ＿ｎ＝６５３００ｃｍ￣２／Ｖ·ｓ，ＧａＳｂ：μ＿ｐ＝５０７６ｃｍ￣２／Ｖ·ｓ。由１０个周期的ＧａＡｓ／ＡｌＡｓ超晶格结构组成的可见光区布拉格反射器已观测到很好的反射光谱和双晶Ｘ射线回摆曲线上高达±２０级的卫星峰。ＧａＡｓ／Ａｌ＿（０．３５）Ｇａ＿（０．６５）Ａｓ量子阱最小阱宽为１０，在ｌｉＫ下由量子尺寸效应导致的光致发光峰能量移动为３９０ｍｅＶ，其线宽为１２ｍｅＶ。这些结果表明上述金属有机化合物已达到较高质量。     

三端1.3μm InGaAsP／InP双区共胺激光器

研制成功了弱调Ｑ及强调Ｑ两种三端１．３μｍ ＩｎＧａ ＡｓＰ／ＩｎＰ双区共腔激光器，其Ｐ／Ｉ特性分别呈二极管激射特性和吸收型双稳特性，两种激光器均实现了室温连续（直流）工作，吸收区电极的设置使两种器件的Ｐ／Ｉ特性均获得了大范围调节。     

气态源分子束外延InGaP／GaAs结构及其在异质结双极晶体管中的应用

本文研究了ＩｎＧａＰ／ＧａＡｓ异质结构的气态源分子束外延（ＧＳＭＢＥ）生长，所得样品晶格失配率△α／α＜８．９５×１０￣（－５），本底载流子浓度为１０￣（１５）ｃｍ￣（－３）数量级，掺硅ｎ型样品的载流子浓度控制范围可达２×１０￣（１５）～４×１０￣（１８）ｃｍ￣（－３）。研究了Ｐ＿２和Ａｓ＿２气氛的切换条件对ＩｎＧａＰ／ＧａＡｓ异质结构界面特性的影响，并成功地生长了ＩｎＧａＰ／ＧａＡｓ异质结双极晶体管（ＨＢＴ）结构材料，用此材料在国内首次制成的ＨＢＴ器件ｆｒ＝２５ＧＨｚ，ｆ＿（ｍａｘ）＝４６ＧＨｚ，电流增益β＝４０，最高可达β＝１５０。     

电子束蒸镀半导体发光二极管的减反射膜

用电子束蒸发设备，制备了用于光纤通信等中的ＧａＡｓ和ＩｎＰ系列双异质结红外发光二级管的减反射介质膜。测量结果表明，对发光波长为０．８５μｍ和０．９０μｍ的ＧａＡｌＡｓ／ＧａＡｓ发光二级管，蒸镀四分之一波长厚的Ａｌ２Ｏ３减反射膜，输出光功率在５０ｍＡ和１００ｍＡ电流注入下，可增加２５￣３５％，最大可增加５０％。但对于１．３μｍ波长的ＩｎＧａＡｓＰ／ＩｎＰ型红外发光二极管，用ＺｒＯ２作减反射膜，比用Ａ     

半导体激光器谱线展宽因子测量

以１．３μｍＤｈ－ＩｎＧａＡｓＰ半导体激光器为研究对象，利用自发辐射谱测量谱线展宽因子，测出了α因子随工作电流变化的关系曲线。     

Real gas choked flow conditions at low reduced-temperatures

Real gas choked mass flux is calculated for a frictionless stream expanding isentropically until it reaches the speed of sound and without phase changes. The other parameters associated with the choked state are the pressure, density, temperature ratios, and the speed of sound. Departure of the choked mass flux from the ideal gas model is discussed first in absolute terms and then in relative terms, using the Principle of Corresponding States, for gases with boiling points in the low temperature range. Reduced-stagnation pressures are examined up to values of 30 for hydrogen, neon, nitrogen, argon, methane, krypton, xenon, and R-14 and up to 100 for ⁴He. The corresponding reduced-stagnation temperatures go down to 1.4 and in some cases down to 1.2 for nitrogen and argon. Also discussed are the limiting values of stagnation parameters for which no phase change occurs in the choked state. Compared to the ideal gas, the mass flux may almost double and the critical pressure ratio may decrease by an order of magnitude. The relevance of results is discussed qualitatively and quantitatively for Joule-Thomson cryocooling.     

As-cast microstructures and behavior at high temperature of chromium-rich cobalt-based alloys containing hafnium carbides

Hafnium is often used to improve the high temperature oxidation resistance of superalloys but not to form carbides for strengthen them against creep. In this work hafnium was added in cobalt-based alloys for verifying that HfC can be obtained in cobalt-based alloys and for characterizing their behavior at a very temperature. Three Co–25Cr–0.25 and 0.50C alloys containing 3.7 and 7.4 Hf to promote HfC carbides, and four Co–25Cr– 0 to 1C alloys for comparison (all contents in wt.%), were cast and exposed at 1200 °C for 50 h in synthetic air. The HfC carbides formed instead chromium carbides during solidification, in eutectic with matrix and as dispersed compact particles. During the stage at 1200 °C the HfC carbides did not significantly evolve, even near the oxidation front despite oxidation early become very fast and generalized. At the same time the chromium carbides present in the Co–Cr–C alloys totally disappeared in the same conditions. Such HfC-alloys potentially bring efficient and sustainable mechanical strengthening at high temperature, but their hot oxidation resistance must be significantly improved.     

Chitosan-collagen/organomontmorillonite scaffold for bone tissue engineering

A novel composite scaffold based on chitosan-collagen/organomontmo-rillonite (CS-COL/OMMT) was prepared to improve swelling ratio, biodegradation ratio, biomineralization and mechanical properties for use in tissue engineering applications. In order to expend the basal spacing, montmorillonite (MMT) was modified with sodium dodecyl sulfate (SDS) and was characterized by XRD, TGA and FTIR. The results indicated that the anionic surfactants entered into interlayer of MMT and the basal spacing of MMT was expanded to 3.85 nm. The prepared composite scaffolds were characterized by FTIR, XRD and SEM. The swelling ratio, biodegradation ratio and mechanical properties of composite scaffolds were also studied. The results demonstrated that the scaffold decreased swelling ratio, degradation ratio and improved mechanical and biomineralization properties because of OMMT.     

Capacitance based mass metering for cryogenic fluids

This paper describes a method for measuring the mass of cryogenic fluids in on-board rocket propellant tanks or ground storage tanks. Linear approximations to the Clausius-Mossotti relationship serve as the foundation for a capacitance based mass sensor, regardless of fluid density stratification or tank shape. Sensor design considerations are presented along with the experimental results for a capacitance based mass gage tested in liquid nitrogen. This test data is shown to be consistent with theory resulting in a demonstrated mass measurement accuracy of ±0.75% and a deviation from linearity of less than ±0.30% of full scale mass. Theoretical accuracies are also shown to be ±0.73% for hydrogen and ±1.39% for oxygen for a select range of pressures and temperatures.     

Equipment using a “static-analytic” method for solubility measurements in potentially hazardous binary mixtures under cryogenic temperatures

A new apparatus designed to study, at cryogenic temperatures, thermodynamic equilibria of potentially explosive binary systems such as hydrocarbon-oxygen mixtures is described herein. This equipment has an equilibrium cell which was especially designed to minimize hazards while allowing accurate phase equilibrium measurements. Reliability of results, obtained with this equipment has been verified by working on the nitrogen-propane system, for which data are already available in literature, over a large range of compositions and at various temperatures. Four isothermal curves describing liquid phase compositions at 109.98, 113.77, 119.75 and 125.63 K have been determined. Our experimental data are represented within 2% in compositions and in pressures through the Peng-Robinson equation of state implying Mathias-Copeman alpha function and Huron-Vidal mixing rule. Comparisons to literature allow pointing out: good agreement is observed with Kremer and Knapp data (1983) while the three sets of Poon and Lu data (1974) presenting systematic positive deviation are consequently judged as suspicious.     

Gas gap thermal switches using neon or hydrogen and sorption pump

The very low pressure obtained thanks to adsorption phenomenon at low temperature can be used to build cryogenic heat switches, which offer the possibility to make or break thermal contact between two parts of a cryogenic system. The ON (conducting) and OFF (insulating) states of the switch are obtained by varying the gas pressure between two copper blocks separated by a gap of 100 μm. This pressure is controlled by acting upon the temperature of a small sorption pump (activated charcoal) connected to the gap space. For a “high” sorption pump temperature, the gas previously adsorbed in the sorption pump is released to the gap between the two blocks, allowing a good thermal conduction through the gas (ON state). On the opposite, cooling the sorption pump allows a very good vacuum between the copper blocks, which efficiently break the thermal contact (OFF state). Experimental thermal characteristics (Conductance in the ON and OFF state, ON-OFF switching temperature) of such a “Gas Gap Heat Switch” are described using hydrogen or neon as exchange gas and are compared with theoretical calculations.     

Development of No-Vent™ liquid hydrogen storage system for space applications

A number of technological advances required to store and maintain normal-boiling-point and densified cryogenic liquids, including liquid hydrogen, under zero boil-off conditions in-space, for long periods of time, have been developed. These technologies include (1) thermally optimized compact cryogen storage systems that reduce environmental heat leak to the lowest-temperature cryogen, which minimizes cryocooler size and input power, and (2) actively-cooled shields that surround the storage systems and intercept heat leak. The processes and tools used to develop these technologies are discussed. A zero boil-off liquid hydrogen storage system technology demonstrator for validating the actively-cooled shield technology is presented.     

Development of a miniature cryogenic fluid circuit and a cryogenic micropump

This article presents the development of a miniaturized cryogenic fluid circuit for distributed cooling of low-temperature tracking detectors in high-energy physics (HEP). The heart of the circuit is a prototype cryogenic micropump. This volumetric pump is compatible with cooling powers of about 10-100 W, and capable of producing pressure heads of up to around 0.3 MPa. Besides detector and electronics cooling in HEP, potential applications are found in the field of superconductor technology.     

Integrated Resonant Self-Pumped Loop and pulse tube cryocooler for cryogenic cooling distribution

Cooling distribution is a vital technology concerning cryogenic thermal management systems for many future space applications, such as in-space, zero boil-off, long-term propellant storage, cooling infrared sensors at multiple locations or at a distance from the cryocooler, and focal-plane arrays in telescopes. These applications require a cooling distribution technology that is able to efficiently and reliably deliver cooling power (generated by a cryocooler) to remote locations and uniformly distribute it over a large-surface area. On-going efforts by others under this technology development area have not shown any promising results.This paper introduces the concept of using a Resonant Self-Pumped Loop (RSPL) integrated with the proven, highly efficient pulse tube cryocooler. The RSPL and pulse tube cryocooler combination generates cooling power and provides a distributive cooling loop that can be extended long distances, has no moving parts, and is driven by a single linear compressor. The RSPL is fully coupled with the oscillating flow of the pulse tube working fluid and utilizes gas diodes to convert the oscillating flow to one-directional (DC) steady flow that circulates through the cooling loop. The proposed RSPL is extremely simple, lightweight, reliable, and flexible for packaging. There are several requirements for the RSPL to operate efficiently. These requirements will be presented in this paper. Compared to other distributive cooling technologies currently under development, the RSPL technology is unique.     

Helium liquefaction with a commercial 4 K Gifford-McMahon cryocooler

This paper describes helium liquefaction using a commercial cryocooler with 1.5 W cooling power at 4.2 K (Sumitomo model RDK415D with compressor CSW-71D, consuming 6.5 kW electrical power), equipped with heat exchangers for precooling the incoming gas. No additional cooling power of cryoliquids or additional Joule-Thomson stages were utilized. Measurements of the pressure dependence of the liquefaction rate were performed. A maximum value of 83.9 g/h was obtained for 2.25 bar stabilized input pressure. Including the time needed to cool the liquefied helium to 4.2 K at 1 bar after filling the bottle connected to the cold head, and correcting for heat screen influences, this results in a net liquefaction rate of 67.7 g/h. Maintaining a pressure close to 1 bar above the bath during liquefaction, a rate of 55.7 g/h was obtained. The simple design enables many applications of the apparatus.