共查询到18条相似文献,搜索用时 94 毫秒
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利用LPCVD方法在Si(100)衬底上获得了3C-SiC外延膜,扫描电子显微镜(SEM)研究表明3C-SiC/p-Si界面平整、光滑,无明显的坑洞形成。研究了以In和Al为接触电极的3C-SiC/p-Si异质结的I-V,C-V特性及I-V特性的温度依赖关系,比较了In电极的3C-SiC/p-Si异质结构和以SiGe作为缓冲层的3C-SiC/SiGe/p-Si异质结构的I-V特性,实验发现引入SiGe缓冲层后,器件的反向击穿电压由40V提高到70V以上。室温下Al电极3C-SiC/p-Si二极管的最大反向击穿电压接近100V,品质因子为1.95。 相似文献
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三螺旋DNA分子poly(dT)·poly(dA)·poly(dT)的构型和振动谱 总被引:4,自引:0,他引:4
我们计算了poly(dT)·poly(dA)·poly(dT)的Howard模型的原子笛卡尔坐标,并利用晶格动力学方法对模型进行了简正分析。结果发现其0 P 0对称振动模式位于804cm-1,这和810cm-1附近没有拉曼和红外谱线的实验结果不符。在800~1000cm-1的范围内只有四个振动模式,明显少于拉曼和红外光谱在该范围内的谱线数目。所以我们认为Howard模型需要进一步地完善和修正,poly(dT)·poly(dA)·poly(dT)必须具有三条不完全一致的脊骨 相似文献
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基于密度泛函理论的广义梯度近似法,对用化学气相沉积法在蓝宝石(α-Al_2O_3)(0001)表面上生长石墨烯进行理论研究.研究结果表明:CH_4在α-Al_2O_3(0001)表面上的分解是吸热过程,由CH_4完全分解出C需要较高能量及反应能垒,这些因素不利于C在衬底表面的存在.在α-Al_2O_3(0001)表面,石墨烯形核的活跃因子并不是通常认为的C原子,而是CH基团.通过CH基团在α-Al_2O_3(0001)表面上的迁移聚集首先形成能量较低的(CH)_x结构.模拟研究(CH)_x对揭示后续石墨烯的形核生长机理具有重要意义. 相似文献
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Rb(NTO)·(H2O)的合成,表征,FT-IR和Raman光谱 总被引:5,自引:0,他引:5
首次用碳酸铷与NTO在水溶液中直接合成了Rb+与NTO-的配合物.采用元素分析和化学分析确定配合物的组成为Rb(NTO)· 相似文献
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γ-Al2O3高温相变的XRD和Raman光谱比较研究 总被引:2,自引:0,他引:2
采用XRD和Raman光谱研究了γ-Al2O3的高温相变.Raman结果表明,位于1 175,1 241 cm-1和1 370,1 400 cm-1的2组谱峰是杂质Fe3 和(或)Cr3 在θ-Al2O3和α-Al2O3环境中产生的荧光光谱,用这2组峰来指认θ-Al2O3和α-Al2O3物相比XRD更灵敏.因此,Raman技术能高灵敏地表征γ-Al2O3的高温相变过程.结果表明γ-Al2O3从800 ℃开始发生相变,γ-Al2O3同时向θ-Al2O3和α-Al2O3转变,随着温度的升高最终完全转变成α-Al2O3.相变温度与样品本身有关. 相似文献
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本文报告了利用高效薄层色谱(TLC)分离技术和表面增强拉曼散射技术(SERS)的结合,建立了分析中草药有效成分槲皮素的新方法。SERS结果揭示出,在TLC原位约3μg样品就可获得槲皮素的主要振动特征谱带。从而阐明了TLC—SERS的有效结合,可对中草药化学成分进行高灵敏度的检测。 相似文献
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采用wolframite前驱物法制备了Pb(Sc1/2Nb1/2)O3陶瓷。通过调节陶瓷烧结工艺,获得了三种具有不同B位离子有序度的PSN陶瓷。测量了三种陶瓷样品在室温至160℃范围内的Raman光谱随温度变化。结果表明,随着温度的升高,三种不同B位有序度的陶瓷样品中,Raman光谱中位于530cm^-1。的F2g模的峰位和半峰宽分别在100℃,85℃和80℃发生了突变,表明陶瓷分别在100℃,85℃和80℃三个温度点发生了铁电-顺电相变。上述结论得到了介电温度谱测量数据的支持。 相似文献
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立方碳化硅(3C-SiC)薄膜通过化学气相沉积(CVD)制备在Si(100)衬底上。本论文主要通过椭偏光谱仪(SE)和拉曼散射仪对3C-SiC薄膜的微观结构和光学性能进行进一步的研究。根据SE的分析获得3CSiC薄膜厚度;根据拉曼散射的分析:可从TO模式和LO模式的线形形状的拟合得到样品的相关长度和载流子浓度。结果表明:该碳化硅(3C-SiC)薄膜质量随膜厚度增加而得到提高,同时分析了外延层厚度对薄膜特性的影响。 相似文献
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Rubn Prez Ivan
tich Michael C. Payne Kiyoyuki Terakura 《Applied Surface Science》1999,140(3-4):320-326
Total-energy pseudopotential calculations are used to study the imaging process in noncontact atomic force microscopy (AFM) on Si(111), Si(100) and GaAs(110) surfaces. The chemical bonding interaction between a localised dangling bond on the atom at the apex of the tip and the dangling bonds on the adatoms in the surface is shown to dominate the forces and the force gradients and, hence, to provide atomic resolution. The lateral resolution capabilities are tested in both the Si(100) and the GaAs(110) surfaces. In the first case, the two atoms in a dimer can be resolved due to the dimer flip induced by the interaction with the tip during the scan, while in the GaAs(110), we identify the anion sublattice as the one observed in the experimental images. 相似文献
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Ch. Zgheib E. Nassar M. Hamad R. Nader P. Masri J. Pezoldt G. Ferro 《Superlattices and Microstructures》2006,40(4-6):638
The effect of the germanium coverage prior to the epitaxial growth of 5 μm thick 3C-SiC on Si(100) substrates were evaluated with Atomic Force Microscopy and μ-Raman spectroscopy. The 3C-SiC layers were grown by atmospheric pressure chemical vapor deposition via a special procedure leading to layers with compressive instead of tensile stress. The Ge amount was varied from 0 up to 2 ML. The obtained results showed that the residual stress inside the layers is shifted in the compressive direction; the crystalline quality is improved with the Ge introduction but on the account of the surface roughness. These results open the route for the use of Ge-modified Si(100) as a potential substrate in order to improve the heteroepitaxial growth of 3C-SiC on silicon substrates. 相似文献
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测量了Si(100)(2×1)-H表面和Si(100)(3×1)-H表面的反射二次谐波强度随温度的变化关系,并与清洁的Si(100)(2×1)表面进行了比较。Si(100)(2×1)表面和Si(100)(3×1)-H表面的二次谐波强度随温度的上升而单调地减小,Si(100)(2×1)-H表面二次谐波强度随温度的变化不是单调的,约在470K时信号最大。可以根据二次谐波信号的强度及其随温度的变化关系来确定样品温度和表面结构。 相似文献
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This paper describes the Raman scattering characteristics of the Raman spectra of 0.4- and 2.0-μm-thick polycrystalline (poly) 3C-SiC on AlN /Si and SiO2/Si by using atmosphere pressure chemical vapor deposition (APCVD) with hexamethyldisilane (HMDS) and carrier gases (Ar+H2). In the Raman spectra for all growth temperatures, the D and G peaks of nanocrystalline graphite were measured. The C/Si rate of poly 3C-SiC deposited in (Ar+H2) atmosphere was higher than that in H2 gas, although HMDS C/Si rate is 3. The biaxial stresses of 2.0-μm-thick 3C-SiC on SiO2 and AlN, which was deposited at the growth temperature of 1180 °C after annealing AlN at 800 and 1100 °C, were calculated as 428 and 896 MPa, respectively. Therefore, poly 3C-SiC should admix with nanocrystalline graphite due to the addition of Ar gas and poly 3C-SiC on SiO2 should be better than on AlN for harsh environmental MEMS applications. 相似文献
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应用第一性原理对CO分子在Co(0001)表面( squar3× squar3)R30°−CO吸附结构进行不同形式的密度泛函计算研究. 结果表明:吸附能修正前,仅RPBE泛函预测CO顶位吸附;而修正后PW91、PBE和PKZB泛函结果也表明CO分子Top顶位吸附最稳定,与实验结果一致.对于吸附几何结构、吸附前后体系功函、C-O伸缩振动频率和CO分子态密度分布,所有泛函给出一致的结果,且与已有实验结果符合. 相似文献
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<正>Epitaxial growth of semiconductor films in multiple-wafer mode is under vigorous development in order to improve yield output to meet the industry increasing demands.Here we report on results of the heteroepitaxial growth of multi-wafer 3C-SiC films on Si(100) substrates by employing a home-made horizontal hot wall low pressure chemical vapour deposition(HWLPCVD) system which was designed to be have a high-throughput,multi-wafer(3×2-inch) capacity. 3C-SiC film properties of the intra-wafer and the wafer-to-wafer including crystalline morphologies,structures and electronics are characterized systematically.The undoped and the moderate NH3 doped n-type 3C-SiC films with specular surface are grown in the HWLPCVD,thereafter uniformities of intra-wafer thickness and sheet resistance of the 3C-SiC films are obtained to be 6%~7%and 6.7%~8%,respectively,and within a run,the deviations of wafer-to-wafer thickness and sheet resistance are less than 1%and 0.8%,respectively. 相似文献