共查询到19条相似文献,搜索用时 46 毫秒
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采用均匀的多孔阳极氧化铝做掩膜在氢化物气相外延设备中生长出高质量的氮化镓膜.采用扫描电镜观察了氮化镓膜的界面性质并用阴极发光谱表征了截面上氮化镓层在不同位置的的发光性质,发现随着厚度的增加,其发光特性得到改善,而且由于掩膜结构的引入,外延膜中的压应力得到一定程度的释放. 相似文献
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多孔型阳极氧化铝膜在纳米结构制备方面的研究和进展 总被引:5,自引:0,他引:5
铝的阳极氧化技术是一种被广泛应用的表面处理方法。近年来,人们发现用这种方法得到的多孔型阳极氧化铝膜(PAA)对于纳米材料的制备有着重要意义。成为国际研究的热点,本文回顾和介绍了铝的阳极氧化技术的机理,工艺和生长规律,介绍了多孔型阳极氧化铝膜在纳米结构制备方面的最新研究进展。 相似文献
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氯气刻蚀中孔碳化钛制备分等级孔结构炭材料 总被引:2,自引:0,他引:2
以钛酸正丁酯为钛源、蔗糖为炭源,采用溶胶-凝胶法制得有机-无机复合干凝胶,后经高温炭热反应、氯气化学刻蚀分别得到中孔碳化钛及碳化物基炭材料(CDCS).通过XRD、Raman、SEM、TEM和氮气吸附等表征,考察了钛酸正丁酯/蔗糖摩尔比例(R)对所制碳化钛和CDCS的孔结构和物理特性的影响.结果表明:在碳热过程所形成的中孔和大孔孔隙能够在氯气刻蚀过程中保持并传递给最终的炭材料.所制CDCS具有三种不同层次的孔隙结构,分别为氯气刻蚀碳化钛品体所产生的微孔、源自蔗糖残留炭中所含的3nm~4nm中孔以及炭颗粒间相互叠加和连接所形成的大孔.通过改变R比值,所制CDCS的BET比表面积和孔容分别在1479m2/g~1640m2/g和1.06cm3/g~2.03cm3/g之间可调. 相似文献
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Fabrication of high-speed polyimide-based humidity sensor using anisotropic and isotropic etching with ICP 总被引:2,自引:0,他引:2
A novel high-speed, high-sensitivity capacitive-type humidity sensor is fabricated by using a new microfabrication process involving combination of directional and isotropic etching with inductively coupled plasma (ICP) etcher and a localized curing of polyimide films on a micro-hotplate. The polyimide humidity sensor is found to have a sensitivity of 0.75 pF/%RH, a linearity of 0.995, a hysteresis of 1.32%RH, a time response of 3 s, and a temperature coefficient of 0.22%RH/°C. This high-sensitivity and high-speed device is achieved using the locally-cured polyimide and a sensor structure having many holes and allowing moisture to diffuse through the top and side surfaces of polyimide film. 相似文献
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We report crack-free and single-crystalline wurtzite GaN heteroepitaxy layers have been grown on Si (111) substrate by metal-organic chemical vapor deposition(MOCVD). Synthesized GaN epilayer was characterized by X-ray diffraction(XRD), atomic force microscope (AFM) and Raman spectrum. The test results show that the GaN crystal reveals a wurtzite structure with the <0001> crystal orientation and XRD ω-scans showed a full width at half maximum (FWHM) of around 583 arcsec for GaN grown on Si substrate with an HT-AlN buffer layer. In addition, the Raman peaks of E2high and A1(LO) phonon mode in GaN films have an obvious redshit comparing to bulk GaN eigen-frequency, which most likely due to tensile strain in GaN layers. But the AO phonon mode of Si has a blueshit which shows that the Si substrate suffered a compressive strain. And we report that the AlN buffer layer plays a role for releasing the residual stress in GaN films. 相似文献
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碱催化多孔二氧化硅薄膜的制备和性能表征 总被引:8,自引:0,他引:8
以水为介质,NH3·H2O为催化剂,丙三醇(C3H5(OH)3和聚乙烯醇(PVA)为添加剂,正硅酸乙脂(TEOS)溶胶 凝胶工艺可制备纳米多孔二氧化硅薄膜。体系的H2O/TEOS>15,TEOS的水解 聚合过程可通过添加剂效应,pH效应等控制。碱催化会使二氧化硅的溶解度增大,也能使二氧化硅胶粒带负电荷,抑制了二氧化硅胶粒之间的聚合长大,而丙三醇与TEOS的水解中间Si(OR)4-x(OH)x结合,抑制其与二氧化硅胶粒的聚合。聚乙烯醇(PVA)能使二氧化硅溶胶具有网状结构,使二氧化硅溶胶易于成膜。该工艺制备的多孔二氧化硅薄膜具有纳米多孔结构。其Vicker硬度在600~800N/mm2,热导率<0.2W·m-1K-1。 相似文献
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选择刻蚀在GaAs工艺中是非常重要的一步。由于湿法腐蚀存在钻蚀和选择性差,且精度难以控制,因此有必要进行干法刻蚀的研究。虽然采用反应离子刻蚀(RIE)、磁增强反应离子刻蚀(MERIE)可以进行选择刻蚀,但是这两种方法在挖槽时会对器件造成较大损伤,影响器件性能。感应耦合等离子刻蚀(ICP)是一种低损伤、高刻蚀速率高选择比的刻蚀方法,在GaAs器件的制造中有突出的优点。本工作进行GaAs/AlGaAs 相似文献
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AbstractWe introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles. 相似文献
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Raman scattering and polarization-dependent synchrotron radiation X-ray absorption, in combination, have been employed to examine the residual stress of undoped GaN epitaxial layers grown on Si by molecular beam epitaxy and Si-doped n-type GaN layers grown on sapphire by metalorganic chemical vapor deposition. Values of the lattice constant of different GaN films can be deduced from the interatomic distances in the second coordination shell around Ga by polarization-dependent extended X-ray absorption fine structure analysis and the strain of the films can be obtained. This result is further confirmed by Raman scattering spectra in which the phonon modes show a significant shift between different GaN epitaxial layers with different growth conditions. 相似文献
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KOH热湿腐蚀法准确估算GaN的位错密度 总被引:1,自引:0,他引:1
实验目的在于解决GaN外延层中六方形腐蚀坑起源问题存在的分歧,并利用腐蚀法准确地估计GaN的位错密度.大量对熔融KOH腐蚀GaN过程中表面形貌的演化以及温度和时间对腐蚀结果影响的实验结果表明,位错类型与腐蚀坑三维形状相对应,而与腐蚀坑大小无关,极性是GaN不同种类位错的腐蚀坑具有不同形状的决定性因素.使所有缺陷都显示出来所需的腐蚀温度和时间呈反比关系.腐蚀法估算GaN位错密度的准确性取决于优化的腐蚀条件和合理的微观观测方法. 相似文献