Preparation of Er2O3 thin films by sol-gel dipping process

Er₂O₃ thin films had been prepared by a sol-gel dipping process with Er(NO₃)₃ · 6H₂O as the precursor and collodion as the viscosity-increasing agent. The annealing temperature of gel films was 600 °C and the thickness of Er₂O₃ thin films increased linearly with the number of dippings at a rate of about 40 nm per dipping. This sol-gel dipping process provided a good reproducibility of the homogeneous Er₂O₃ thin films. The spectral and crystal properties of the thin films were studied in detail and the results indicated that the color of the thin films mainly resulted from an interference effect. Moreover, the optically transparent region of Er₂O₃ thin films was determined with photoacoustic spectroscopy.     

Fabrication and characterization of highly luminescent Er3+:Al2O3 thin films with optimized growth parameters

Erbium doped amorphous alumina thin films were fabricated using Co-sputtering technique in various depositions runs with varying parameters for optimizing the deposition parameters to obtain the films with best optical performance. The main subject of investigation includes the effects of change in various deposition parameters such as substrate heating, radio frequency (RF) power and oxygen pressure inside the chamber while deposition. High quality as-deposited films with various Er concentrations and low carbon content have been confirmed by XPS. Substrate heating ∼500 °C was found to be very effective in getting highly dense films with high refractive index of 1.70 at 1530–1570 nm emission band. The Er³⁺-doped films showed very intense near-infrared luminescence peak at 1550 nm even without any post-deposition annealing treatment.     

Zn^2＋掺杂的YBCO薄膜的超导性能研究

采用溶胶-凝胶法在LaAlO3（LAO）单晶衬底上制备了Zn^2＋掺杂的YBCO薄膜,用X射线衍射（XRD）、高分辨透射电子显微镜（HRTEM）以及标准四引线法分别研究了Zn^2＋掺杂的YBCO薄膜的微观结构、生长取向以及超导性能。结果表明,随Zn2＋掺杂浓度的增大薄膜的临界电流密度提高,而临界转变温度下降、临界转变温区变宽;但当掺杂量〉0.5%（摩尔分数）时,会影响YBCO的c轴取向生长,导致超导性能变差。通过优化掺杂比例后得到Zn2＋掺杂0.5%（摩尔分数）的YBCO薄膜具有最好的综合超导性能,其TC为91.3K,ΔT为1.1K,Jc约为1.54MA/cm^2（77K,0T）。     

Fabrication and spectroscopic broadening properties for 1.5 microm amplification of Er(3+)-doped BaF2 nanoparticles

We show the potential application of Er(3+)-doped BaF2 nanoparticles prepared from microemulsion technology for 1.5 microm amplification in telecommunication. Nanoparticles with different sizes of about 8, 10, and 20.5 nm were prepared. The XRD patterns showed the excursion of diffraction peaks. When the particle size is smaller or the diffraction angle is larger, this kind of excursion will be more serious. The emission bands of Er3+ at 1.54 microm for the three particle sizes at were as follows: 8 nm particles--145 nm, 10 nm particles--124 nm, and 20.5 nm particles--82 nm (full width at half maximum, FWHM), or 173, 153, 97 nm (deltalambda(eff)), respectively. In all the three cases, the emission spectra were flat from 1.53 to 1.56 microm.     

溶胶凝胶法制备Er3+-Yb3+共掺纳米SiO2粉

利用溶胶-凝胶法合成了Er2O3-Yb2O3-SiO2纳米二氧化硅(SiO2)粉。Er3 和Yb3 直接加入有机酸催化的TEOS反应溶液中,凝胶后经过700~900℃,得到Er3 -Yb3 共掺纳米SiO2粉。样品经过红外光谱、XRD、TEM等分析,结果表明,纳米粉的粒径受有机酸比例和处理温度的影响。在室温PL谱上,样品可观察到较强的1530nm荧光,同时镱的引入对掺铒SiO2纳米粉在1.54μm的荧光发射有增强作用。     

Improved infrared emissions of Er(3+)-Tm3+ co-doped Al2O3 thin films: the role of cross relaxation among rare earth ions

We report the infrared emissions of Er(3+)-Tm3+ co-doped amorphous Al2O3 thin films pumped at 791 nm by a Ti:sapphire laser. The as-deposited films were annealed to improve the photoluminescence performance. Three cross relaxation channels among Er(3+)-Tm3+ and Tm(3+)-Tm3+ ions incorporated in the films were investigated as annealing temperature increases especially from 800 to 850 degrees C. In order to understand the Stark effect and cross relaxations, the photoluminescence spectra were deconvoluted by Gaussian fittings. Our results indicate that the luminescence intensity of 1.62 microm in comparison to 1.5 microm can be enhanced by the cross relaxation process [Er3+ (4I13/2) + Tm3+ (3H6) --> Er3+ (4I15/2) + Tm3+ (3F4)], and the longer-wavelength side of Er3+ emission can be improved by the CR process [Er3+ (4I15/2) + Tm3+ (3H4) --> Er3+ (4I3/2) + Tm3+ (3F4) at expense of the Tm3+ 1.47 microm emission which is also maybe quenched by the CR effect between themselves. These results suggest one possible approach to achieve broadband infrared emissions at the wavelength region of 1.45-1.65 microm from the Er(3+)-Tm3+ co-doped systems.     

退火对Cr3+离子掺杂Al2O3薄膜的结构及发光性能影响

用脉冲激光沉积技术在Si(100)基底上制备了纯Al2O3、掺杂浓度为0.3%、1%(质量分数)的Cr3+∶Al2O3薄膜。制备态的薄膜为立方γ-Al2O3结构,经800℃真空条件下退火1h样品的结晶度有所提高,呈现α-Al2O3相与γ-Al2O3相的衍射峰。薄膜基本保持了靶材中原有各元素成分比例,平均粒径为250nm,形貌为条形。与Al2O3粉体相比,制备态薄膜在386nm处的发光峰强度明显提高。这可归因于薄膜中氧空位的增加使双氧空位吸收电子所产生的F2+色心浓度提高。薄膜经真空退火后在332、398nm附近的发光峰强度明显增强,这是由于薄膜中氧空位的增加提高了F+、F色心浓度。与此同时,制备态薄膜在386nm附近发光峰经退火后由386nm蓝移至381nm,可归因于退火后制备态薄膜的内应力得到了释放。1%(质量分数)Cr3+掺杂薄膜在646、694nm出现Cr3+离子由4 T2能级跃迁至4 A2能级及由E-能级跃迁至4 A2能级产生的荧光发光峰。     

Al/Al2O3多层膜的研究

用真空蒸镀及自然氧化方法在玻璃基底上制备纳米量级的4、5、6、7对层的Al／Al2O3多层膜。采用称重法测定薄膜的厚度；在常温和低温下使用三点法测定多层膜的电特性；用扫描电镜（sEM）观察薄膜的表面和截面的形貌及成分。结果表明：制备的是纳米量级非晶态的Al／Al2O3多层膜，在常温和低温（77K）下均具有类似负阻的特性。     

溶胶／凝胶法制备纳米TiO2／Al2O3

采用溶胶-凝胶法制备纳米TiO2／Al2O3，考察了陈化温度及络舍比对TiO2／Al2O3比表面积及孔结构参数的影响。结果表明，TiO2／Al2O3平均粒径〈70nm，比表面积超过210m^2／g，平均孔径0．8-1．4nm。适当降低陈化温度及加络合剂有利于TiO2／Al2O3粒子的分散。Al2O3的存在提高了TiO2／Al2O3的热稳定性。     

掺Er-Al2O3薄膜发光特性的研究

通过离子束辅助沉积(IBAD)在热氧化SiO2上沉积Al2O3薄膜,在120keV下注入5×10115cm-2Er离子,Ar气氛下773～1273K退火1h.低温下测试PL谱线,随退火温度升高,发光强度上升.973K退火下发光强度特别低,并观察到Si衬底的1140nm峰.光透射谱表明几乎在所有的测试范围内尤其在1530nm处973K退火样品的透射谱强度最强,波导损耗最低.1530nm发光强度随退火温度的变化跟发光强度的变化相反.说明Er离子在514.5nm泵谱吸收界面σ跟Al2O3的光吸收损耗有一定关系.     

Phase transition of Er3+-doped Al2O3 powders prepared by the non-aqueous sol–gel method

The Er³⁺-doped Al₂O₃ powders have been prepared by the non-aqueous sol–gel method using the aluminum isopropoxide as precursor, acetylacetone as chelating agent, nitric acid as catalyzer, and hydrated erbium nitrate, as dopant under isopropanol environment. The phase structure and phase transition of the Er³⁺-doped Al₂O₃ powders were investigated by using thermogravimetry/differential thermal analysis (TG/DTA), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The phase contents diagram for the Er-doped Al–O system with the doping concentration up to 5 mol% was described at the sintering temperature from 550 to 1250 °C. There were the three crystalline types of Er³⁺-doped Al₂O₃ phases, γ-, θ- and α-(Al, Er)₂O₃, and the two relative stoichiometric compounds composed of Al, Er, and O, ErAlO₃ and Al₁₀Er₆O₂₄ phases in the Er–Al–O phase contents diagram. The Er³⁺ doping suppressed crystallization of the γ and θ phases and delayed phase transition of the γ → θ and θ → α. The increased Er³⁺ doping concentration and the elevated sintering temperature enhanced the precipitation of the ErAlO₃ and Al₁₀Er₆O₂₄ phases. The preparation procedure for the Er³⁺-doped Al₂O₃ powders in the non-aqueous sol–gel process, including chelating, hydrolysis, peptization, doping and gelation, has a significant effect on the phase formation and its transition for the Er³⁺-doped Al₂O₃ powders.     

Absorption and emission cross sections of Er(3+) in Al(2)O(3) waveguides

Al(2)O(3) slab waveguide films were doped with erbium using ion implantation to a peak concentration of 1.5 at. %. Prism coupling measurements show absorption caused by (4)I (15/2) ?(4)I (13/2) intra-4f transitions in Er(3+) with a maximum at 1.530 mum of 8 dB/cm. The Er(3+) absorption cross section is determined as a function of wavelength. We used the McCumber theory to derive the emission cross section spectrum from the absorption results, which we then compared with the Er(3+) photoluminescence spectrum. The peak absorption and emission cross sections are found to be 6 x 10(-21) cm(-2). The results are used to predict the optical gain performance of an Er-doped Al(2)O(3) optical amplifier that operates around 1.5 mum.     

La2O3-doped BaTiO3 thin films obtained by pulsed laser deposition

Abstract

La²O³-doped barium titanate (BaTiO³) thin films have been obtained by pulsed laser deposition. The structure and quality of deposited films were characterized by X-ray diffraction and scanning electron microscopy. A smooth surface was obtained when the films were deposited in 30 Pa ambient oxygen. The composition (elements and oxides) of the thin films were close to those of the target. The layer obtained by pulsed laser deposition from a target of BaTiO³ doped with 0.5 at.% La exhibits good dielectric characteristics: capacitance 88 pF, Curie temperature 59°C and dielectrics loss, tanδ, 0.084.     

连续含铝SiC自由膜的制备与发光特性研究

通过自制喷膜装置对聚铝碳硅烷(PACS)进行脱泡处理、熔融纺膜,并对其进行氧化交联、高温预烧及高温裂解终烧可制得连续含铝SiC自由薄膜.用扫描电镜(SEM)分析薄膜的形貌,通过红外光谱(FT-IR)分析氧化交联后薄膜的结构变化,通过电子探针(EPMA)、拉曼光谱(Raman)、X射线衍射(XRD)与场发射高分辨透射电子显微镜(HRTEM)对薄膜进行成分及微观结构分析,采用光致发光谱(PL)对薄膜的光学带隙和发光特性进行了研究.结果表明,熔融纺膜法与PACS先驱体法相结合可制得均匀、致密的耐高温连续舍铝SiC自由薄膜,室温下表现出了320～440nm宽谱带发光,其发光峰可分别归因于α-SiC和C簇,且随着烧结温度的提高,发光强度增大.     

SiO2-Sm2O3 vitreous films via the sol-gel method

SiO₂-Sm₂O₃ vitreous films 120 nm thick were obtained via the sol-gel method. Infrared, energy-dispersive analysis of X-rays, spectroscopic ellipsometry and absorption spectroscopy showed a total inclusion of samarium in the silica matrix, which remains amorphous up to 1000 °C. The inclusion of the samarium ion increases the porosity. The optical properties of films were investigated by spectro-ellipsometry, and the parameters obtained were compared with those obtained by other techniques.     

Nonlinear absorption of thin Al2O3 films at 193 nm

Absorption of thin Al(2)O(3) films was measured at 193 nm with an ArF-laser calorimeter. In addition to the expected high linear absorption coefficient, we found, for the first time to our knowledge, that two-photon absorption and transient color-center formation are nonnegligible loss channels in thin films at 193 nm. The nonlinear absorption coefficient is of the order of several times 10(-4) cm/W.     

稀土Nd掺杂Ba_(0.65)Sr_(0.35)TiO_3薄膜的微结构与光致发光性能研究

用溶胶-凝胶法制备了不同浓度(0、1%、3%、5%(摩尔分数))的Nd掺杂钛酸锶钡(Ba0.65Sr0.35TiO3,BST)薄膜.XRD结果表明,经700℃退火1h后,样品晶化为完整的多晶钙钛矿结构,平均晶粒尺寸为20nm.原子力显微镜(AFM)观察发现,薄膜表面均匀致密,光滑平整.室温光致发光谱(PL)显示在808nm氩离子激光激发下,Nd掺杂的BST薄膜在876、1060、1337nm处有较强的近红外(NIR)发光,分别对应于Nd3+的4F3/2-4I9/2、4F3/2-4I11/2、4F3/2-4I13/2跃迁.这些结果表明Nd掺杂BST薄膜在激光器和光放大器等光电器件领域有着广泛的应用前景.     

Surface structure of silver thin films on In2O3:Sn and Al2O 3 †

Surface structure of thin silver films (200 Å) on two technologically important films, indium tin oxide (ITO) and aluminium oxide, has been studied using scanning tunneling microscope. ITO films were prepared by reactive electron beam evaporation. Aluminium oxide films were prepared by oxidizing 2000 Å thick aluminium films evaporated on to H₂ terminated single crystal silicon substrates. The surface structure of silver on ITO and aluminium oxide appeared to be same and was characteristic of Stranski-Krastanov type. The observed asymmetry in the island shape was attributed to the anisotropic nature of the strain fields surrounding the nucleation centres.