GROWTH MODEL OF TEXTURED DIAMOND (111) FILM IN CH4/O2/H2 ATMOSPHERE

Partially oriented and highly textured diamond films on Si( 111 ) substrates were achieved by hot-filament chemical vapor deposition(HFCVD). High nucleation density greater than 5×10⁸cm^-2 was realiged in 3 min by near-surface glow discharge. The os-grown films were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and Raman spectroscopy. It was found that by adding a small amount of oxygen to the mixture of CH₄/H₂, the appearance of facet(111) was well controlled, and the secondary nucleation on the facet(111) was suppressed greatly. Growth feature of homoepitaxy on diamond (111) surface was demonstrated to be in Stranski-Krastanov model by SEM.     

氦气对MPCVD沉积金刚石的影响

为了确定添加氦气对微波等离子体化学气相沉积(MPCVD)金刚石膜的影响,采用发射光谱法(OES)在线诊断了CH₄-H₂-He等离子体的发射光谱特性,研究了He对等离子体内基团空间分布的影响;并利用扫描电子显微镜(SEM)和拉曼(Raman)光谱对不同He体积分数下沉积出的金刚石膜进行了表征。结果表明：随着He体积分数的增加,等离子体内H_α, H_β, H_γ, CH和C₂基团的谱线强度均呈上升趋势,其中H_α基团的谱线强度增加最大。光谱空间诊断发现He的加入导致等离子体中各基团的空间分布均匀性变差,造成沉积出的金刚石膜厚度极不均匀。沉积速率测试表明,He的加入导致碳源基团相对浓度增加,有利于提高薄膜的沉积速率,当He体积分数由0 vol.%增加至4.7 vol.%时,沉积速率提高了24%。SEM测试结果表明,随着He体积分数的增加,金刚石膜表面形貌由(111)晶面取向向晶面取向混杂转变,孪晶生长明显。高He(4.7 vol.%)体积分数下由于C₂基团的相对浓度较高,导致二次形核密度增加。此外,由于基片台受到等离子体的刻蚀和溅射作用,导致薄膜沉积过程中引入了金属杂质原子。二次形核和杂质原子的存在使得孪晶大量的产生,薄膜呈现出压应力。     

Cu掺杂SnO_2/TiO_2复合薄膜的制备及性能研究

制备Cu掺杂的纳米Sn O2/Ti O2溶胶,采用旋涂法在载玻片上镀膜,经干燥、煅烧制得Cu掺杂的Sn O2/Ti O2薄膜,通过对比实验探讨掺杂比例、条件、复合形式等对结构和性能的影响。采用XRD、SEM、EDS、UVVis等测试手段对样品进行表征,并以甲基橙为探针考察了其光催化降解性能。XRD测试结果显示薄膜的晶型为锐钛矿型,结晶度较高。SEM谱图显示薄膜表面无明显开裂,粒子分布均匀,粒径约为20 nm。EDS测试结果表明薄膜材料中含有Cu元素,谱形一致。UV-Vis吸收光谱表明Cu掺杂以及Sn O2/Ti O2的复合使得在近紫外区的光吸收比纯Ti O2明显增强。光催化实验表明Cu掺杂后使得Sn O2/Ti O2复合薄膜对甲基橙的光催化降解效率进一步提高,Sn O2/Ti O2复合薄膜的光催化活性在10%Cu掺杂时达到最高。     

Substrate dependent growth studies of MgB2 films by electrocrystallization

The comparative study of MgB₂ film growth on Al₂O₃ and glass substrate by electrocrystallization technique is discussed. The precursor magnesium films were deposited by vacuum evaporation method. These magnesium films were then used as electrode for the growth of MgB₂ films by electrocrystallization. The structural, morphological and superconducting properties of the electrocrystallized MgB₂ films on Al₂O₃ substrate were examined by using XRD, SEM and electrical resistivity measurement techniques and compared with that of MgB₂ films grown on glass substrate. The films deposited on Al₂O₃ substrates showed enhanced crystallinity and relatively higher T_c value compared to films deposited on glass substrates.     

MgO(111)衬底MgB2 超薄膜的制备和性质研究

利用混合物理化学气相沉积法(HPCVD)在MgO(111)衬底上制备了干净的MgB₂超导超薄膜. 在背景气体压强, 载气氢气流量以及沉积时间一定的情况下, 改变B₂H₆的流量, 制备得到不同厚度系列的MgB₂超导薄膜样品, 并测量了其超导转变温度 T_c, 临界电流密度J_c等临界参量. 该系列超导薄膜沿c轴外延生长, 表面具有良好的连接性, 且有很高的超导转变温度T_c(0) ≈ 35-38 K和很小的剩余电阻率ρ(42 K) ≈ 1.8-20.3 μΩ·cm^-1. 随着膜厚的减小而减小, 临界温度变低, 而剩余电阻率变大. 其中20 nm的样品在零磁场, 5K时的临界电流密度J_c ≈ 2.3×10⁷ A/cm². 表明了利用HPCVD在MgO(111)衬底上制备的MgB₂超薄膜有很好的性能, 预示了其在超导电子器件中广阔的应用前景. 关键词： MgO(111)衬底 2超薄膜')" href="#">MgB₂超薄膜 混合物理化学气相沉积     

Synthesis of YBa2Cu3O7−x superconducting thin films on LaAlO3 by means of PAMOCVD

High-T_c superconducting thin films have been deposited in situ by means of a plasma assisted metal-organic chemical vapour deposition (PAMOCVD) process on LaAlO₃. An EMCORE high-speed rotating disc reactor was used to deposit the films at a substrate temperature of 600°C to 800°C. The system is equipped with a (remote) 120 W microwave plasma generator. The oxidising plasma gas is N₂O and/or O₂ while Ar was used as the inert carrier gas for the different metal-organics. The influence of different process parameters (such as the temperatures of the metal-organics, substrate temperature, and plasma gas composition) on the superconductive properties and on the morphology of the films was investigated. Surface morphology and composition were studied by SEM/EDX or EPMA, and AC susceptibility measurements were used to investigate the superconductive properties (T_c and J_c). X-ray diffraction measurements indicated that single-phase YBa₂Cu₃O_7−x films were epitaxially grown with the 00l orientation perpendicular to the substrate surface. The critical temperature (T_c) of the films is about 90 K and the critical current density (J_c) is higher than 10⁶ A/cm² at 77 K and zero field.     

Surface and interface characteristics of TiO2–muscovite nanocomposites

The morphology and chemical characteristics of the surface and the interface of TiO₂–muscovite nanocomposites were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Our results clearly showed that TiO₂ grains formed on the TiO₂ thin film surface, whereas the presence of TiO₂ grains on the interface between TiO₂ thin films and the muscovite substrates was not obvious. While euhedral rutile grains were found in samples doped with Zn ions, none were found in samples doped with Sn ions. The XPS results showed that cations present in the muscovite substrates diffused into the TiO₂ thin films. Etching measurements revealed that diffusion abilities of cation impurities varied: Si and Al diffused more easily than K. The observed differences in chemical composition and oxidation of the elements, especially on the surface and the subsurface, may influence the different crystallization behaviors of elements in TiO₂ thin films and the different active degree of elements diffusing from muscovite substrates.     

Structural,optical,and electrical properties of Cu-doped ZrO_2 films prepared by magnetron co-sputtering

Copper(Cu)-doped ZrO_2(CZO) films with different Cu content(0 at.%～ 8.07 at.%) are successfully deposited on Si(100) substrates by direct current(DC) and radio frequency(RF) magnetron co-sputtering. The influences of Cu content on structural, morphological, optical and electrical properties of CZO films are discussed in detail. The CZO films exhibit ZrO_2 monocline(ˉ111) preferred orientation, which indicates that Cu atoms are doped in ZrO_2 host lattice. The crystallite size estimated form x-ray diffraction(XRD) increases by Cu doping, which accords with the result observed from the scanning electron microscope(SEM). The electrical resistivity decreases from 2.63 ?.cm to 1.48 ?·cm with Cu doping content increasing, which indicates that the conductivity of CZO film is improved. However, the visible light transmittances decrease slightly by Cu doping and the optical band gap values decrease from 4.64 eV to 4.48 eV for CZO films.     

添加Fe(C5H5)2合成氢掺杂金刚石大单晶及其表征

在Ni₇₀Mn₂₅Co₅-C体系中添加含氢化合物Fe(C₅H₅)₂作为新型氢源, 利用温度梯度法, 在压力为5.5-6.0 GPa、温度为1280-1400 ℃的条件下, 成功合成出氢掺杂的宝石级金刚石大单晶. 通过傅里叶显微红外光谱发现, 随着Fe(C₅H₅)₂添加量的增加, 合成晶体中与氢相关的对应于sp³杂化C-H键的对称伸缩振动和反对称伸缩振动的红外特征峰2850和2920 cm^-1逐渐增强, 而晶体中氮含量却逐渐减少. 通过合成晶体的拉曼光谱分析发现, 金刚石的拉曼峰伴随Fe(C₅H₅)₂的添加向高频偏移, 这表明氢的进入在金刚石内部产生了压应力. 观察扫描电子显微镜图像发现, 在低含量Fe(C₅H₅)₂添加时晶体表面平滑, 而高含量添加时晶体表面缺陷增多, 且呈现出气孔状. 使用新的添加剂Fe(C₅H₅)₂作为氢源, 合成出含氢宝石级金刚石单晶, 丰富了金刚石单晶中对氢的研究内容, 也可为理解天然金刚石的形成机理提供帮助.     

The adsorption of carbon monoxide on TiO2(110) supported palladium

Palladium overlayers deposited on TiO₂(110) by metal vapour deposition have been investigated using LEED, XPS and FT-RAIRS of adsorbed CO. Low coverages of palladium (<3 ML) deposited at 300 K adsorb CO exclusively in a bridged configuration with a band (B₁ at 1990 cm⁻¹) characteristic of CO adsorption on Pd(110) and Pd(100) surfaces. When annealed to 500 K, XPS and LEED indicate the nucleation of Pd particles on which CO adsorbs predominantly as a strongly bound linear species which we associate with edge sites on the Pd particles (L* band at 2085 cm⁻¹). Both bridged and linear CO bands are exhibited as increases in reflectivity at the resonant frequency, indicating the retention of small particle size during the annealing process. Palladium overlayers of intermediate coverages (10–20 ML) deposited at 300 K undergo some nucleation during growth, and adsorbed CO exhibits both absorption and transmission bands in the B₁ (1990 cm⁻¹) and B₂ (1940 cm⁻¹) regions. The latter is associated with the formation of Pd(111) facets. Highly dispersed Pd particles are produced on annealing at 500 K. This is evidenced by the dominance of transmission bands for adsorbed CO and a significant concentration of edge sites, which accommodate the strongly bound linear species at 300 K. Adsorption of CO at low temperature also allows the identification of the constituent faces of Pd and the conversion of Pd(110)/(100) facets to Pd(111) facets during the annealing process. High coverages of palladium (100 ML) produce only absorption bands in FT-RAIRS of adsorbed CO associated with the Pd facets, but annealing these surfaces also shows a conversion to Pd(111) facets. LEED indicates that at coverages above 10 ML, the palladium particles exhibit (111) facets parallel to the substrate and aligned with the TiO₂(110) unit cell, and that this ordering in the particles is enhanced by annealing.     

Ce∶ LSO多晶薄膜的溶胶-凝胶法制备及其发光性能

采用Pechini溶胶-凝胶法结合旋涂工艺在单晶硅(111)上制备了Ce3+离子掺杂的硅酸镥(Lu2SiO5)薄膜,利用热重差热分析(TG-DSC)、X射线衍射(XRD)、扫描电镜(SEM)、真空紫外光谱(VUV)及椭偏(SE)测试对Ce∶ Lu2SiO5薄膜的物相、形貌、发光性质和光学常数进行了表征.结果表明:薄膜样...     

Ni/SnO_2复合薄膜的制备与光电性能

采用旋涂法将溶胶-凝胶法制备的Ni/Sn O2凝胶在玻璃基底上镀膜,得到了Ni/Sn O2复合薄膜,探讨了镍掺杂量、煅烧温度对薄膜结构和形貌的影响。通过X射线衍射、红外光谱、扫描电子显微镜等测试手段对Ni/Sn O2复合膜的结构和形貌进行表征。结果显示,500℃下煅烧的薄膜样品的结晶度较高,粒径小,颗粒分布均匀。用紫外-可见分光光度计和四探针电阻仪对其进行光学、电学性能测试,结果显示:适量的Ni掺杂可以提高Sn O2薄膜在近紫外光区的吸收,Ni/Sn O2薄膜在近紫外光区的吸收随着Ni2+掺杂摩尔分数从5%增加到10%而逐渐减小。当Ni2+掺杂摩尔分数为6%时,Ni/Sn O2复合薄膜的导电性能最好。     

Epitaxial growth and thermostability of cubic and hexagonal SrMnO3 films on SrTiO3(111)

The growth of SrMnO₃ films on SrTiO₃(111) substrates by pulsed laser deposition was studied and found to produce cubic and hexagonal (4H) structures in the SrMnO₃ films. By adjusting the substrate temperature and oxygen pressure, the stability of the two phases was fine-tuned, resulting in the growth of cubic-SrMnO₃(111) or 4H-SrMnO₃(0001) film, with the 4H phase being the more stable at room temperature and ambient pressure in the bulk form. The growth temperature of the cubic phase was also further lowered relative to the bulk thermodynamics by strain at the heterointerface, and once obtained, it was stable at temperatures of up to 800 °C.     

Annealing effects on the properties of Ga2O3 thin films grown on sapphire by the metal organic chemical vapor deposition

We have prepared the gallium oxide (Ga₂O₃) thin films on sapphire substrates by the metal organic chemical vapor deposition (MOCVD) technique. We have compared the two films with and without the thermal annealing by using the X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and the photoluminescence (PL) spectra. Postdeposition annealing of amorphous Ga₂O₃ films was found to increase the degree of crystallization and the surface roughness. The PL emission intensities of bands in the blue–green and the ultraviolet regions increased by the thermal annealing.     

Structural, optical and electrical studies on pulse electrodeposited CdIn2S4 thin films

CdIn₂S₄ thin films were prepared by pulse electrodeposition technique over F:SnO₂ glass and stainless steel substrates in galvanostatic mode from an aqueous acidic bath containing CdSO₄, InCl₃ and Na₂S₂O₃. The growth kinetics of the film has been studied and the deposition parameters such as electrolyte bath concentration, bath temperature, time of deposition, deposition current and pH of the bath are optimized. X-ray diffraction (XRD) analysis of the as deposited and annealed films shows polycrystalline nature. Energy dispersive analysis by X-ray (EDAX) confirms nearly stoichiometric CdIn₂S₄ nature of the film. Scanning electron microscope (SEM) studies show that, the deposited films are well adherent and grains are uniformly distributed over the surface of the substrate. The optical transmission spectra show a direct band gap of 2.16 eV. Conductivity measurements have been carried out at different temperatures and electrical parameters such as activation energy, trapped energy state and barrier heights etc. have been determined.     

B2O3添加宝石级金刚石单晶的生长特性

利用温度梯度法, 在5.3-5.7 GPa压力、1200-1600 ℃的温度条件下, 将B₂O₃粉添加到FeNiMnCo+C合成体系内, 进行B₂O₃添加宝石级金刚石单晶的合成. 研究得到了FeNiMnCo触媒生长B₂O₃添加宝石级金刚石单晶的相图分布规律. 结果表明B₂O₃添加会使晶体生长的“V”形区上移和低温六面体单晶生长区间变宽. 通过晶体生长实验, 研究合成了不同形貌的B₂O₃添加宝石级金刚石单晶. 研究同时证实, B₂O₃的过量添加会对宝石级金刚石单晶生长带来不利影响. 当B₂O₃的添加量高于约3 wt‰、生长时间超过20 h时, 很难实现优质B₂O₃添加宝石级金刚石单晶的生长. 但B₂O₃的适量添加(不超过1 wt‰), 有助于提高低温板状六面体宝石级金刚石单晶的成品率. 通过对晶体生长速度的研究发现, B₂O₃的添加使得优质晶体的生长速度明显降低, 随着晶体生长时间的延长, B₂O₃添加剂对晶体生长的抑制作用会越发明显. 扫描电镜测试结果表明, 合成体系内B₂O₃添加剂的引入, 导致晶体表面的平整度明显下降.     

Study of the interfacial structure and chemistry of CVD κ-Al2O3/TiC multilayer coatings

This article describes the interfacial regions in CVD grown TiC/κ-Al₂O₃ multilayers. A number of microanalytical techniques were used including HREM, EDX and EELS. Occasionally, the first 50 nm of the alumina layers deposited on the intermediate TiC layers grew as a cubic alumina, heavily faulted, containing small amounts of sulphur (S), maybe as a stabiliser. The presence of slightly rounded TiC (111) facets may act as preferred nucleation sites for the cubic Al₂O₃ phase, with a ‘cube on cube’ orientation relationship. In this way the nucleation of κ-Al₂O₃ is less favourable. After some tens of nanometres the cubic phase cannot be stabilised any longer and the layer continues to grow as κ-Al₂O₃. A number of observations point towards the reaction zone (RZ) being η- and/or γ-Al₂O₃. The diffraction work and the FFT analysis of the HREM images show that the RZ is an fcc phase with a=7.9 Å, which matches with η- and γ-Al₂O₃. The EELS Al fine structure indicate more tetrahedral Al ions than in κ-Al₂O₃, as in η- and γ-Al₂O₃. The RZ contains small amounts of S, as has been reported for γ-Al₂O₃. Due to the structural similarities between η- and γ-Al₂O₃ it was not possible to determine which of these cubic phases is present in the RZ.     

金属-有机骨架[Zn(BDC)(H2O)2]n膜的原位制备及其对硝基苯类有机物的可逆检测

采用水热法,将锌片与对苯二甲酸(H2BDC)反应原位合成[Zn(BDC)(H2O)2]n薄膜.利用XRD和SEM分别对薄膜的结构、形貌和尺寸等进行了表征.结果表明,薄膜是由一维链状结构的金属-有机骨架材料纳米晶构成的,随着水热时间的增加,薄膜中的[Zn(BDC)(H2O)3]n纳米晶晶粒尺寸逐渐减小.该薄膜在紫外光的激...     

基于FTO/VO2/FTO结构的VO2薄膜电压诱导相变光调制特性

采用直流磁控溅射和后退火工艺在掺氟的SnO₂(FTO)导电玻璃衬底上制备VO₂薄膜, 研究了不同退火时间和不同比例的氮氧气氛对VO₂薄膜性能的影响, 对VO₂薄膜的结晶取向、表面形貌、表面元素的相对含量和透过率随波长变化进行了测试分析, 结果表明在最佳工艺条件下制备得到了组分相对单一的VO₂薄膜. 基于FTO/VO₂/FTO结构在VO₂薄膜两侧的透明导电膜上施加电压并达到阈值电压时, 观察到了明显的电流突变. 当接触面积为3 mm×3 mm时, 阈值电压为1.7 V, 阈值电压随接触面积的增大而增大. 与不加电压的情况相比, FTO/VO₂/FTO结构在电压作用下高低温的红外透过率差值可达28%, 经反复施加电压, 该结构仍保持性能稳定, 具有较强的电致调控能力.     

氮气氛下(100)织构金刚石薄膜的成核与生长研究

利用热丝化学气相沉积法研究了氮气浓度对金刚石薄膜成核和生长的影响.实验发现氮气的 加入对金刚石成核密度影响不大,但促进了已形成的金刚石核的长大.适量的氮气不仅使金 刚石生长速率得到很大的提高,而且稳定了金刚石薄膜(100)面的生长,使金刚石薄膜具有 更好的(100)织构.利用原位光发射谱对衬底附近的化学基团进行了研究.研究表明,氮气的 引入使得金刚石生长的气相化学和表面化学性质发生了很大变化.含氮基团的萃取作用提高 了金刚石表面氢原子的脱附速率,从而提高了金刚石膜的生长速率.而含氮基团的选择吸附 使金刚石 关键词： 氮气 金刚石薄膜 织构 原位光发射谱