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1.
UHV／CVD生长SiGe／Si材料分析及应用研究 总被引：1，自引：1，他引：0
以Si2H6和GeH4为生长气源,采用UHV／CVD系统在Si（100）衬底上生长了Sil—xGex合金和Sil—xGex／Si多量子阱结构。采用X射线双晶衍射仪、扫描电子显微镜和原子力显微镜等仪器设备对样品的组份、界面和表面形貌等晶体质量进行了研究。SiGe合金中Si和Ge摩尔分数的比值随着Si2H6和GeH4流量比的增加按比例线性增加,比例因子为2．57。生长的Si0．88Ge0．12合金样品的界面清晰,表面平整,平均粗糙度仅为0．4nm,位错密度低于104／cm2。六周期Si0．88Ge0．12／Si多量子阱的X射线双晶衍射摇摆曲线中存在多级卫星峰和Pendellosung条纹。这些结果表明SiGe合金和SiGe／Si多量子阱均具有很好的晶体质量。 相似文献
2.
Xi-qiang Li 《上海大学学报(英文版)》2000,4(2):163-166
Single crystal Ga
x
In1−x
As films have grown up on GaAs(100) substrate at 375°C and on InP(100) substrate at 390°C, respectively, by the method of
rf-sputtering with using undoped GalnAs polycrystal as target. However, on Si(100) or Si(111) substrates at 260–390°C, even
at 465°C, only polycrystalline films were obtained. In addition, the structure, composition, electrical characteristic and
optical properties of the Ga
x
In1−x
As films were investigated using X-ray diffraction (XRD), reflection of high energy electron diffraction (RHEED), energy dispersion
analyzer of X-ray (EDAX), Hall measurements and spectroscopic ellipsometry. 相似文献
3.
ＥｐｉｔａｘｉａｌＧｒｏｗｔｈｏｆＹＳＺａｓＢｕｆｅｒＬａｙｅｒｓｆｏｒＨｉｇｈＴｃＳｕｐｅｒｃｏｎｄｕｃｔｉｎｇＦｉｌｍｓｏｎＳｉＳｕｂｓｔｒａｔｅｓＱｉａｎＷｅｎｓｈｅｎｇ（钱文生）ＬｉｕＲｏｎｇ（刘融）ＷｅｉＴｏｎｇｌｉ（魏同立）（Ｍｉｌｒｏｅ... 相似文献
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Ethene/norbornene copolymerization by the catalyst system [Me2Si(3-tertBuCp)(NtertBu)]TiCl2/MAO was investigated in detail at 30 °C, 60 °C, and 90 °C. A mass flow controller was used in this work to obtain kinetic
data and investigate temperature's effects on activity, norbornene incorporation, copolymerization parameter, microstructure,
glass transition temperature, and molar masses were described. High copolymerization valuesr
ξ and high alternation are determined. The number of isotactic alternating sequences is much higher than that of the syndiotactic
alternating sequences. 相似文献
6.
在硅锗合金衬底上采用氧化等制膜方式生成零维和二维的纳米结构样品，用高精度椭偏仪(HPE)、卢瑟福背散射谱仪(RBS)和高分辩率扫描透射电子显微镜(HR—STEM)测量样品的纳米结构．并采用美国威思康新州立大学开发的Rump模拟软件进行精细结构模拟．并测量出样品横断面锗纳米团簇和纳米层的PL谱。在硅锗合金的氧化层表面中首次发现纳米锗量子点组成的几个纳米厚的盖帽膜结构．首次提出的生成硅锗纳米结构的优化加工条件的氧化时问和氧化温度匹配公式的理论模型与实验结果拟合得很好． 相似文献
7.
INTRODUCTION Monocrystalline SBN (Strontium barium nio-bium, SrxBa1?xNb2O6, denoted SBNx?100, where 0.25≤x≤0.75) solid solution, is currently being inves-tigated as potential material for many micro-device applications, such as piezoelectric infrared detectors, piezoelectric, electro-optic modulators, and holo-graphic storage (Koch et al., 1998), because SBN has one of the largest known linear electro-optic coeffi-cients (r33=1300 pm/V for SBN75), two orders of magnitude larger th… 相似文献
8.
绝缘体上的锗硅（SiGe．On．Insulator,SGOI）材料不仅是高迁移率新型沟道材料应变硅的良好衬底,其本身也是一种极具潜力的高迁移率衬底材料．Ge浓缩是获得高Ge组分、高质量SGOI的最优制备方法之一,传统Ge浓缩工艺在实验中得到改进,在高纯N2气氛中,进行了1000oC的后退火以改善所得SGOI中Ge元素的分布．实验制备了三种后退火条件下的Ge浓缩样品以作对比,并在三种样品上分别外延了20nm厚的顶层Si以进一步确定所得SGOI材料性能．实验结果发现。三种样品表面平整度并无太大差别,而使用了改进后退火工艺的样品具有最好的Ge组分均匀性和最低的缺陷密度．同时,改进后退火工艺的样品上外延所得顶层硅具有最大的应变值,而Si／SiGe界面处Ge的组分是顶层硅应变度的决定性因素之一． 相似文献
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10.
以Si衬底上外延Ge薄膜为吸收区,研究了Si基Ge光电探测器的材料生长与器件制作工艺,并对材料晶体质量和器件性能进行表征分析。Ge薄膜是采用低温缓冲层技术在超高真空化学气相沉积系统上生长的。1μm厚Ge薄膜的表面仅出现纳米量级的岛,表面粗糙度只有1.5 nm。Ge薄膜的X射线衍射峰形对称,峰值半高宽低于100 arc sec。Ge薄膜中存在0.14%的张应变。Si基Ge光电探测器在-1 V偏压时暗电流密度为13.7 mA/cm2,在波长1.31μm处的响应度高达0.38 A/W,对应外量子效率为36.0%,响应波长扩展到1.6μm以上。 相似文献
11.
TiO2 fibers were prepared via alternatively introducing water vapor and Ti precursor carried by N2 to an APCVD （chemical vapor deposition under atmospheric pressure） reactor at ≤200 ℃. Activated carbon fibers （ACFs） were used as templates for deposition and later removed by calcinations. The obtained catalysts were characterized by scanning electron micros- copy （SEM）, transmission electron microscopy （TEM）, Brunauer, Emmett and Teller （BET） and X-ray diffraction （XRD） analysis The pores within TiO2 fibers included micro-range and meso-range, e.g., 7 nm, and the specific surface areas for TiO2 fibers were 141 m^2/g and 148 m^2/g for samples deposited at 100 ℃ and 200℃ （using ACFI700 as template）, respectively. The deposition temperature significantly influenced TiO2 morphology. The special advantages of this technique for preparing porous nano-material include no consumption of organic solvent in the process and easy control of deposition conditions and speeds. 相似文献
12.
Cu(In,Ga)Se2 (CIGS) precursor films were deposited on Mo/glass by electrodeposition, and then annealed in Se vapor. The annealing temperature ranged from 450 °C to 580 °C, and two heating rates were selected. The results showed that the crystalline quality of the CIGS films and formation of the Cu-Se compound could be strongly influenced by the selenization temperature and heating rate. Raman spectroscopy and X-ray diffraction (XRD) analysis showed that when the selenization temperature was increased from 450 °C to 550 °C, the amount of binary CuSe phase decreased and the amount of Cu2Se increased. After annealing at 580 °C, a minimum amount of Cu2?xSe compounds was obtained and the degree of CIGS film crystallinity was higher than in other samples. The relationship between the properties of the film and the heating rate was studied. XRD and Raman spectra showed a decrease in the Cu2?xSe phase with increasing heating rate. Scanning electron microscopy (SEM) and XRD showed a remarkable increase in the grain size of CIGS during rapid heating. 相似文献
13.
The influence of calcination temperature on TiO2 nanotubes＇ catalysis for TiO2/UV/03 was investigated. TiO2 nanotubes （TNTs） were prepared via the sol-gel method and calcined at 300--700 ℃, which were labeled as TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700, respectively. TNTs were characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. It is found that TNTs calcined at 400 ℃ showed the best thermal stability. When the calcination temperature increased from 400 ℃ to 700 ℃, the special structure of tubes was destroyed and gradually converted into nanorods and/or particles. The transformation from anatase to rutile occurred at 600 ℃, and the rutile phase was enhanced when the calcination temperature was increased to over 600 ℃. The calcina- tion temperature＇s influence on TNTs＇ adsorption activity for for TiO2/UV/O3 was investigated in landfill leachate solution chemical oxygen demand （COD） and catalytic activity In landfill leachate solution, the adsorption activity of COD decreased in the reduced order of TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700. In photocatalytic ozonation, TNTs-400 showed the best catalytic activity while TNTs-700 exhibited the worst. In other three processes, the COD removal of TNTs-300/UV/O3 was higher than those of TNTs-500/UV/O3 and TNTs-600/UV/O3 in the first 20 rain, and then became close to those of the latter two in the following 40 rain. Compared with TNTs-300 and TNTs- 400, TNTs-600 had the best anti-fouling activity, while TNTs-500 and TNTs-700 had lower anti-fouling activity than the former three. In photocatalytic ozonation, the calcination temperature of 400 ℃ was appropriate when TNTs were obtained at the synthesis temperature of 105 ℃. 相似文献
14.
LIAO Bang-liang MA Jian-guang ZHU Wei-hu ZHU Hong-mei YANG Kai LIU Yan-hong Li Huai-lin WANG Xiao-jing WANG Xin-lin 《重庆大学学报(英文版)》2018,17(1):17-26
To improve the oxidation resistance and corrosion resistance of Zr-4 alloy, titanium nitride(TiN) coatings were prepared on the Zr-4 alloy with a TiN ceramic target with different ratios of N_2. Microstructure and high-temperature properties of the TiN coated samples were studied by scanning electron microscopy(SEM), energy dispersive spectrometer(EDS), X-ray diffraction meter(XRD), X-ray photoelectron spectroscopy(XPS), heat treatment furnace and autoclaves, respectively. The x value of the TiN coatings(TiN_x) ranges from 0.96 to 1.33. After the introduction of N_2, TiN coating exhibits a weak(200) plane and a preferred(111) orientation. The coating prepared with an N_2 flow ratio of 15% shows an optimal oxidation resistance in the atmospheric environment at 800 °C. In either 1 200 °C steam environment for one hour, or deionized water at 360 °C and a pressure of 18.6 Mpa for 16 d, the opitimized TiN coated samples have no delamination or spallation; and the gains in the masses of samples are much smaller than Zr-4 alloy. These results demonstrate the effectiveness of the optimized TiN coating as the protective coating on the Zr-4 alloy under extreme conditons. 相似文献
15.
Response to temperature stress of reactive oxygen species scavenging enzymes in the cross-tolerance of barley seed germination 总被引：1，自引：0，他引：1
A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood.
In this study, we used the germination of barley seeds as a system to investigate the cross-tolerance of low-temperature pretreatment
to high-temperature stress and the possible involvement of reactive oxygen species (ROS) scavenging enzymes in the cross-tolerance.
After pretreatment at 0 °C for different periods of time, barley seeds were germinated at 35 °C, and the content of malondialdehyde
(MDA) and the activities of ROS scavenging enzymes were measured by a spectrophotometer analysis. The results showed that
barley seed germinated very poorly at 35 °C, and this inhibitive effect could be overcome by pretreatment at 0 °C. The MDA
content varied, depending on the temperature at which seeds germinated, while barley seeds pretreated at 0 °C did not change
the MDA content. Compared with seeds germinated directly at 35 °C, the seeds pretreated first at 0 °C and then germinated
at 35 °C had markedly increased activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and
glutathione reductase (GR). The SOD and APX activities of seeds germinated at 35 °C after 0 °C-pretreatment were even substantially
higher than those at 25 °C, and GR activity was similar to that at 25 °C, at which the highest germination performance of
barley seeds was achieved. These results indicate that low-temperature pretreatment can markedly increase the tolerance of
barley seed to high temperature during germination, this being related to the increase in ROS scavenging enzyme activity.
This may provide a new method for increasing seed germination under stress environments, and may be an excellent model system
for the study of cross-tolerance. 相似文献
16.
黎锡强 《上海大学学报(英文版)》2000,4(2)
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｓｐｕｔｔｅｒｉｎｇｔｅｃｈｎｉｑｕｅｗｅｌｌｓｕｉｔｓｔｈｅｇｒｏｗｔｈｏｆｃｏｍｐｏｕｎｄｓａｎｄａｌｌｏｙｓ ,ｗｈｏｓｅｅｌｅｍｅｎｔａｌｃｏｎｓｔｉｔｕｅｎｔｓｈａｖｅｓｉｇｎｉｆｉｃａｎｔｌｙｄｉｆｆｅｒｅｎｔｍｅｌｔｉｎｇ ｐｏｉｎｔｓａｎｄｖａｐｏｒｐｒｅｓｓｕｒｅｓ.ＡｃｏｎｓｉｄｅｒａｂｌｅａｍｏｕｎｔｏｆｗｏｒｋｓａｂｏｕｔｒｆｓｐｕｔｔｅｒｄｅｐｏｓｉｔｉｏｎｏｆｂｉｎａｒｙⅢ Ⅴｃｏｍｐｏｕｎｄｆｉｌｍｓｈａｓｂｅｅｎｐｕｂｌｉｓｈｅｄ[1～… 相似文献
17.
Lattice-matched InAlN/AlN/GaN high electron mobility transistors (HEMTs) grown on sapphire substrate by using low-pressure metallorganic chemical vapor deposition were prepared, and the comprehensive DC characteristics were implemented by Keithley 4200 Semiconductor Characterization System. The experimental results indicated that a maximum drain current over 400 mA/mm and a peak external transconductance of 215 mS/mm can be achieved in the initial HEMTs. However, after the devices endured a 10-h thermal aging in furnace under nitrogen condition at 300 ℃, the maximum reduction of saturation drain current and external transconductance at high gate-source voltage and drain-source voltage were 30% and 35%, respectively. Additionally, an increased drain-source leakage current was observed at three-terminal off-state. It was inferred that the degradation was mainly related to electron-trapping defects in the InAlN barrier layer. 相似文献
18.
Modeling and optimization of catalytic dehydration of ethanol to ethylene using central composite design 总被引：1，自引：0，他引：1
The central composite design in the modeling and optimization of catalytic dehydration of ethanol to ethylene was performed
to improve the ethylene yield. A total of 20 experiments at random were conducted to investigate the effect of reaction temperature,
Si/Al ratios of H-ZSM-5 catalyst and liquid hourly space velocity (LHSV) on the ethylene yield. The results show that the
relationship between ethylene yield and the three significant independent variables can be approximated by a nonlinear polynomial
model, with R-squared of 99.9% and adjusted R-squared of 99.8%. The maximal response for ethylene yield is 93.4% under the optimal condition of 328 °C, Si/Al ratio 85,
and LHSV 3.8 h−1. 相似文献
19.
王万录 《重庆大学学报(英文版)》2003,2(2)
1. Introduction Recently, carbon nanotubes have attracted a lot of interest because of their outstanding electrical properties and their potential application as a possible material for fabrication of cold cathodes [1-3]. It was found that the field enhancement from carbon nano-tubes exhibited large local field enhancement and considerable field emission currents at relatively low applied voltage. Carbon nanotube-based field emission displays have been fabricated using well-aligned nano-tubes … 相似文献
20.
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation,
different cultivation temperatures, ranging from 39 °C to 28 °C, were evaluated in shake flask. The result indicated that
37 °C was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated
at 30 °C. This result was verified by batch fermentation in 5-L bioreactor under 37 °C and 30 °C temperature, respectively.
The specific cell growth rate at 37 °C was higher than that at 30 °C during earlier stage of cultivation. The maximum value
[5.5 U/(h·g DCW)] of elastase formation rate occurred at 24 h at 30 °C compared to 4.6 U/(h·g DCW) at 30 h at 37 °C. Based
on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the
next study. When compared to single temperature of 37 °C or 30 °C, both two-stage temperature shift strategy and oscillatory
temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass
(both 8.6 g/L) was achieved at 30 h at 37 °C, but at 42 h using two-stage temperature cultivation strategy. The highest elastase
production (652 U/ml) was observed at 30 °C in batch process. It was concluded that cultivation at constant temperature of
30 °C was appropriate for elastase production by Bacillus sp. EL31410.
Project (No. 20276064) supported by the National Natural Science Foundation of China 相似文献