二氧化钒薄膜在α-Al2O3衬底上的外延生长及其金属-半导体相变特性研究

利用ＸＲＤ及ＸＲＤ极图技术表征了用激光剥离技术生长的ＶＯ２薄膜。结果表明：在衬底温度为５００℃,氧气偏压６．６７Ｐａ的条件下,在α－Ａｌ２Ｏ３（１１２０）衬底上能实现ＶＯ２的二维外延生长。薄膜的结构除了与沉积工艺有关外,还和衬底的取向密切相关。     

聚乙烯醇(PVA)对无支撑氧化铝膜微观结构的影响

聚乙烯醇（ＰＶＡ）能够避免溶胶－凝胶法制备的Ａｌ_２Ｏ_３膜在干燥阶段产生微裂纹,同时也对Ａｌ_２Ｏ_３膜的微观结构产生影响．利用ＸＲＤ、ＤＴＡ、ＴＧＡ、ＦＴ－ＩＲ及Ｎ_２吸附等手段研究掺杂ＰＶＡ对Ａｌ_２Ｏ_３膜的物相组成、热稳定性以及比表面积、孔径分布、孔表面分形性等微观结构的影响．研究表明,经过４００℃煅烧ＰＶＡ完全排除．与纯Ａｌ_２Ｏ_３膜相比,添加ＰＶＡ的Ａｌ_２Ｏ_３膜吸附量较大,比表面积有所增大,但并不随着ＰＶＡ含量的增多而增加．ＰＶＡ有利于 Ａｌ_２Ｏ_３膜孔径的调整,使孔径分布更狭窄,孔体积也有较大程度的增加．随着 ＰＶＡ的加入,Ａｌ_２Ｏ_３膜的孔表面分形维数降低．     

共沸蒸馏法制备超细氧化铝粉体及其表征

用改进的溶胶－凝胶法（ｓｏｌ－ｇｅｌ）制备了单分散纳米级Ａｌ_２Ｏ_３粉体,研究了不同干燥方法对产品粒子性能的影响．结果表明,共沸蒸馏法能够有效地对氢氧化铝凝胶脱水,防止了硬团聚体的形成．在１１５０℃的温度下煅烧,可制得尺寸分布均匀、呈球形的α－Ａｌ_２Ｏ_３超细粉体,其平均粒径为６８ｎｍ．以透射电镜（ＴＥＭ）、Ｘ射线衍射（ＸＲＤ）、热重（ＴＧ）、差热（ＤＴＡ）、比表面测定（ＢＥＴ）等手段对所得的超细Ａｌ_２Ｏ_３粉体进行了表征．     

共沉淀法制备YAG-Al2O3纳米复合粉体

本文采用共沉淀法制备了ＹＡＧ－Ａｌ_２Ｏ_３纳米复合粉体．并通过ＸＲＤ、ＴＥＭ详细研究了粉体组成、形貌随煅烧温度的变化．研究表明,在１３００℃下煅烧可获得ＹＡＧ粒径约１００ｎｍ、分散均匀、无杂相的ＹＡＧ－Ａｌ_２Ｏ_３纳米复合粉体．粉体在１４５０℃可热压烧结致密,远低于文献报道的热压烧结温度１６００℃．用共沉淀法制备ＹＡＧ－Ａｌ_２Ｏ_３纳米复合粉体具有成本低、产量高和工艺简单的优点．     

溶胶-凝胶法制备莫来石粉体

通过溶胶－凝胶法制备了高纯超细莫来石先驱体．并运用ＸＲＤ和ＩＲ等手段对其晶化行为进行了研究．发现新制备的莫来石凝胶由拜耳石（Ａｌ（ＯＨ）_３）和无定型氧化硅组成,它经由γ－Ａｌ_２Ｏ_３和铝硅尖晶石,在１２５０℃转化为莫来石．所得到的莫来石粉体晶粒细小,呈薄片状．     

纳米Au团簇在氧化钛修饰的介孔分子筛MCM-41中的组装

以钛酸丁酯为ＴｉＯ_２前驱体,使ＴｉＯ_２均匀分散于纯硅介孔分子筛ＭＣＭ－４１的介孔孔道内表面,利用ＴｉＯ_２光学性质将ＡｕＣｌ－４还原为Ａｕ（０）并组装于氧化钛修饰的ＭＣＭ－４１孔道中．对所合成的Ａｕ负载的氧化钛修饰的ＭＣＭ－４１进行了ＸＲＤ,ＸＰＳ,Ｎ_２吸附－脱附曲线,及固体ＵＶ－Ｖｉｓ漫反射等多种结构表征．由ＸＰＳ谱和固体ＵＶ－Ｖｉｓ漫反射吸收光谱的ｐｌａｓｍｏｎ吸收峰证明Ａｕ团簇呈现０价的金属状态．     

表面诱导沉淀法制备Al2O3-ZrO2纳米复合粉体

采用表面诱导沉淀法,制备了Ａｌ_２Ｏ_３－ＺｒＯ_２（１５ｖｏｌ％）纳米复合粉料,利用透射电子显微镜对其形貌进行了表征．结果表明：在ｐＨ＝５时,可以使ＺｒＯ_２前驱体均匀地包裹在Ａｌ_２Ｏ_３颗粒表面,经过８００℃煅烧之后,Ａｌ_２Ｏ_３颗粒表面均匀地结合着粒径约为３０ｎｍ的ＺｒＯ_２颗粒,ＺｒＯ_２颗粒尺寸均匀．该粉体经过２４ｈ球磨和超声波处理之后,未发生ＺｒＯ_２颗粒脱落现象,表明ＺｒＯ_２颗粒与Ａｌ_２Ｏ_３颗粒表面结合紧密．     

直流磁控反应溅射制备IrO2薄膜

为研究氧化依（ＩｒＯ_２）对ＰＺＴ铁电薄膜疲劳性能的影响,利用直流（ＤＣ）磁控反应溅射（ｓｐｕｔｔｅｒｉｎｇ）工艺成功地在ＳｉＯ_２／Ｓｉ（１００）衬底上制得了高度取向的ＩｒＯ_２薄膜．并在其上制成ＰＺＴ铁电薄膜．讨论了溅射参数（溅射功率、 Ａｒ／Ｏ_２比、衬底温度）以及退火条件对氧化铱薄膜的结晶、取向和形态的影响．     

嵌有纳米碳颗粒凝胶玻璃的制备及其发光特性

以磷酸三乙酯、硝酸铝和正硅酸乙酯为原料,通过它们的水解制备了ｘＡｌ_２Ｏ_３·ｘＰ_２Ｏ₅·１００ＳｉＯ_２（ｘ＝０．２５～３）凝胶．在６００℃对凝胶进行热处理,使其中的有机基团炭化,从而制备出了镶嵌有碳纳米颗粒的ｘＡｌ_２Ｏ_３·ｘＰ_２Ｏ_５·１００ＳｉＯ_２（ｘ＝０．２５,０．５）凝胶玻璃．在室温下以５３２ｎｍ激光（Ｎｄ：ＹＡＧ）激发,在 ６３０ｎｍ处有一强的发光峰,该发光现象是由镶嵌在凝胶玻璃中的纳米碳颗粒产生的．     

高分子网络凝胶法制备纳米α-Al2O3粉体

用高分子网络凝胶法制备Ａｌ_２Ｏ_３粉体,通过网络的阻碍作用,阻止Ａｌ_２Ｏ_３的团聚,获得颗粒大小在 １０ｎｍ左右的α－Ａｌ_２Ｏ_３粉体,其煅烧温度比通常低 １００℃．     

Microstructure Characterization of Sol-gel Prepared MoO3-TiO2 Thin Films for Oxygen Gas Sensors

Binary metal oxide MoO3-TiO2 films have been prepared using the sol-gel technique. The thin films were annealed at several temperatures including 400℃,450℃,500℃,550℃ and 600℃ for lhour. The morphology, crystalline structure and chemical composition of the films have been analysed using SEM,XRD,RBS and XPS techniques. The SEM analysis showed that the films annealed at 450℃ are mainly smooth and uniform with 20-100nm-sized grains and with few particles as large as a micrometre or more. The XRD analysis revealed that the films annealed at 400℃ were a mixture of orthorhombic and hexagonal MoO3phases. The films annealed at 450℃ increased in hexagonal phase. The preferential orientation growth along(100) plane of the hexagonal phase and (010) plane of the orthorhombic phase has been found in both samples. RBS and XPS analysis showed that the films were stoichiometric. When the annealing temperature is increased to more than 500℃, the concentration ratio of MoO3 to TiO2 decreased due to the evaporation of MoO3. For the study of the electrical and gas sensing properties, films were deposited on sapphire substrates with interdigital electrodes on the front-side and a Pt heater on the backside. The O2 gas sensing properties of MoO3-TiO2 thin films are discussed.     

Preferred growth of epitaxial TiN thin film on silicon substrate by pulsed laser deposition

Epitaxial TiN thin films on silicon substrates were prepared by pulsed excimer laser (KrF, 34 ns) ablation of a hot-pressed TiN target in nitrogen gas atmosphere. X-ray diffraction (XRD) showed that the preferred orientations of TiN thin films did not change with substrate temperatures, nitrogen gas pressure and film thickness; however, they did change with the orientations of substrates. The epitaxial orientation relationships between high-quality epitaxial TiN thin films and silicon substrates [2 4 2] TiN [2 4 2] Si, (1 1 1) TiN(1 1 1) Si and [3 1 1] TiN [3 1 1] Si, (1 0 0) TiN(1 0 0) Si. The full-width at half-maximum (FWHM) of the rocking curve of XRD and the minimum channelling yield of Rutherford backscattered spectroscopy (RBS) of the epitaxial TiN thin film were estimated to be 0.3 ° and 7.3%, respectively, indicating excellent crystalline quality of the grown film. X-ray photoelectron spectroscopy confirmed that the binding energies of Ti 2p 3/2 and N 1s core levels in epitaxial thin film were 455.2 and 397.1 eV, respectively, corresponding to those of TiN bulk. By calibrating the RBS spectra, the chemical composition of TiN thin films was found to be titanium-rich. The typical surface roughness of TiN thin film observed by scanning probe microscopy was about 1.5 nm. © 1998 Chapman & Hall     

Preparation and characterization of ultra-thin cobalt silicide for VLSI applications

Ultra-thin cobalt silicide (CoSi₂) was formed from 10 nm cobalt film by solid phase reaction of Co and Si by use of rapid thermal annealing (RTA). The Ge⁺ ion implantation through Co film caused the interface mixing of the cobalt film with the silicon substrate and resulted in a homogeneous silicide layer. XRD was used to identify the silicide phases that were present in the film. The metallurgical analysis was performed by RBS. XRD and RBS investigations showed that final RTA temperature should not exceed 800°C for thin (< 50 nm) CoSi₂ formation.     

ZnO thin films deposited by a CVT technique in closed ampoules

ZnO thin films were prepared on quartz glass, Si (100), and sapphire (001) substrates by a chemical vapour transport (CVT) technique. During the growing processes, the source and substrate temperatures were maintained at 1000 °C and 600 °C, respectively. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements showed that the crystalline qualities of ZnO thin films were sensitively dependent on substrates. ZnO thin film deposited on sapphire substrate exhibited the best morphology with the largest crystallite size of more than 20 μm. Meanwhile, the XRD patterns showed that ZnO thin film deposited on sapphire substrate was strongly c-axis preferred-oriented with high crystalline quality. The optical properties of ZnO thin films were investigated by photoluminescence (PL) spectroscopy at room temperature (RT). The results suggested that the optical properties of ZnO thin films were highly influenced by their crystalline qualities and surface morphologies.     

Preparation and characterization of LiNiVO4 powder and non-stoichiometric LiNixVyOz films

Inverse spinel type structured oxide, LiNiVO₄, was synthesized by using solid-state method and the crystalline powder was characterized by Rietveld refinement and X-ray photoelectron spectroscopy. Non-stoichiometric lithium nickel vanadate thin films were prepared by physical vapour deposition technique. The amorphous films were characterized by Rutherford back-scattering spectroscopy (RBS), nuclear reaction analysis (NRA), Auger electron spectroscopy (AES), X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analytical methods. Films crystal growth at various temperatures was also studied by XRD and SEM. The HRTEM analysis of sputtered film shows nanocrystalline domains of NiO and LiNiVO₄ phases with characteristic lattice parameters of the host compound and the results correlate well with the XRD data. Electrochemical properties of the films were discussed.     

Optical properties of the c-axis oriented LiNbO3 thin film

C-axis oriented Lithium Niobate (LiNbO₃) thin films have been deposited onto epitaxially matched (001) sapphire substrate using pulsed laser deposition technique. Structural and optical properties of the thin films have been studied using the X-ray diffraction (XRD) and UV-Visible spectroscopy respectively. Raman spectroscopy has been used to study the optical phonon modes and defects in the c-axis oriented LiNbO₃ thin films. XRD analysis indicates the presence of stress in the as-grown LiNbO₃ thin films and is attributed to the small lattice mismatch between LiNbO₃ and sapphire. Refractive index (n = 2.13 at 640 nm) of the (006) LiNbO₃ thin films was found to be slightly lower from the corresponding bulk value (n = 2.28). Various factors responsible for the deviation in the refractive index of (006) LiNbO₃ thin films from the corresponding bulk value are discussed and the deviation is mainly attributed to the lattice contraction due to the presence of stress in deposited film.     

真空还原制备的VO2热致相变薄膜Raman光谱和红外光谱研究

报道了利用真空还原制备的VO2薄膜的红外透射光谱和Raman光谱,并进行370－900nm波段的光透射测试以及900nm波长的热滞回线特性测试,表明所制备VO2薄膜具有优良的热致相变光学特性,结晶状态不同的薄膜其Raman谱位置有明显改变,室温时的红外光谱表现出较好的红外振动特性。讨论了薄膜结晶状态对Raman位移的影响以及VO2薄膜的红外光谱。     

Interface reactions between titanium thin films and (1¯1 2) sapphire substrates

We have studied the reactivity of Ti with the R-plane (1ˉ1 2) of sapphire from room temperature to 1250 °C by X-ray photoemission spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Rutherford backscattering spectroscopy (RBS). The combination of these techniques allowed the interface reactions to be studied from the monolayer regime up to the bulk regime. XPS showed that at room temperature, monolayer coverages of Ti reduced the sapphire surface to form Ti-O and Ti-Al bonds. TEM, XRD, and RBS showed that annealing of room-temperature deposited Ti resulted in an interfacial region consisting of two layers, a Ti₃Al[O] layer adjacent to the sapphire and a Ti_0.67 [O_0.33] layer at the free surface. The growth of the Ti₃Al[O] layer had an activation energy of 103.4±25 kJ deg-mole. The nature of the interfacial reaction between Ti and sapphire was similar for Ti coverages from the monolayer to the bulk regime.     

Room-temperature growth of AlN/TiN epitaxial multi-layer by laser molecular beam epitaxy

We have fabricated epitaxial AlN thin films at room temperature on sapphire (0001) substrates with a TiN (111) epitaxial buffer layer by pulsed laser deposition in ultra-high vacuum (laser molecular beam epitaxy method). The TiN buffer layers were also fabricated at room temperature. Four-circle X-ray diffraction analysis and reflection high-energy electron diffraction results indicate the heteroepitaxial structure of AlN (0001)/TiN (111)/sapphire (0001) with the epitaxial relationship of AlN [10-10]||TiN [11-2]||sapphire [11-20]. The surface of the room-temperature grown AlN film was found to be atomically flat, reflecting the nano-stepped surface of ultrasmooth sapphire substrates. Then, we could achieve the room-temperature epitaxial growth of [AlN/TiN] multi-layer. The temperature dependence of resistivity of the AlN/TiN multi-layer film was also measured.     

Effect of deposition temperature on the properties of sputtered YIG films grown on quartz

Yttrium Iron Garnet (YIG), Y₃Fe₅O₁₂, is an oxide material that has potential applications in the magneto-optical recording media and microwave device industries. These materials, when synthesized in thin film form, usually require post-deposition annealing in order to enhance their physical properties. Furthermore, integration of YIG based optical components requires the synthesis of high quality YIG material on quartz, a process that may be problematic due to poor adhesion and lattice mismatch. Thus, we have conducted a study on the effect of deposition temperature (from 25 to 800 °C) and post-deposition annealing (at 740 °C) on the crystalline quality and chemical composition of YIG thin films, grown by radio-frequency magnetron sputtering, on quartz substrates. X-ray diffraction (XRD) shows that as-grown layers are amorphous, and subsequent annealing is necessary to induce film crystallization. Rutherford backscattering spectrometry analyses were also conducted and the chemical composition of the films was found to depend on initial deposition temperature and is affected by post-deposition anneals. Comparison of the XRD and RBS results point out to the existence of an optimal deposition temperature at about 700 °C for the formation of high crystalline quality and stoichiometric YIG thin films. Magnetic measurements were found to correlate to the XRD and RBS analyses.