IR spectroscopic studies of periodic columnar nanostructures of anodic titanium oxide

The experimental specimens consisted of periodic columnar nanostructures of anodic titanium oxide (average dimension≈60 nm) that were produced by anodic oxidation of the two-layer thin-film composition Ti−Al in a solution of oxalic acid that was followed by vacuum annealing. The structures formed were studied by electron microscopy and reflection IR spectroscopy. It is found that the nanodimensional columns consist predominantly of quasiamorphous Ti dioxide in the form of rutile and anatase with minimum inclusions of Ti₂O₃ and TiO. Vacuum annealing decreases the content of TiO₂ and increases that of Ti₂O₃ and TiO in the oxide columns. These changes characterize dissolution of oxygen from the composition of the columnar structures in a residual film of metallic Ti. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 200–204, March–April, 1998.     

脉冲磁控溅射法制备单斜相氧化铒涂层

用中频脉冲反应磁控溅射法,在溅射功率为78 W,93 W和124 W以及衬底温度分别为室温,500 ℃及677 ℃下制备了氧化铒涂层.采用原子力显微镜、纳米压痕、X射线衍射和掠入射X射线衍射法研究了涂层的形貌、力学性能及物相结构.测量了涂层的电学性能.结果显示,脉冲磁控溅射沉积氧化铒涂层具有较高的沉积速率.实验制备得到了单斜相结构的氧化铒涂层.提高溅射功率时,沉积速率从28 nm/min增大至68 nm/min,涂层的结晶质量显著下降.提高衬底温度至500 ℃和677 ℃时,单斜相衍射峰强度下降.分析认为 关键词： 氧化铒 脉冲磁控溅射 单斜晶相     

CdSeS量子点的光吸收谱亚结构和光致发光激发谱分析

用光致发光激发(PLE)谱分析吸收谱的亚结构。实验样品是共熔法制备的CdSeS量子点玻璃,量子点的生长时间分别为2h和4h,高分辨透射电子显微镜(HRTEM)分析得到样品中量子点的平均直径分别为3．6nm和3．8nm。在室温下对样品进行了光吸收谱和光致发光激发谱研究。光吸收谱显示了量子尺寸效应,光致发光激发谱中低能端有两个明显的峰。考虑价带简并以及电子与空穴之间的相互作用,通过理论分析和数值计算,得到1S3/2-1Se和2S3/2-1Se的跃迁能量及其随量子点半径的变化,由此确认光致发光激发谱中的两个峰分别为1S3/2-1Se和2S3/2-1Se跃迁。     

Photoluminescence of Si-based nanotips fabricated by anodic aluminum oxide template

Large-area, high-density silicon-based nanotips were fabricated using electrochemical lithography. The morphology and optical properties of the samples were characterized by atomic force microscopy and photoluminescence. The distribution and size of the silicon-based nanotips were uniform. Two photoluminescence peaks were observed at 585 and 620 nm. The peak centered at 585 nm exhibited a narrow full-width at half maximum. No evident peak energy shift was observed when the measurement temperature was increased from 10 K to room temperature, which suggested that the photoluminescence should be attributed to the interface states and/or defects in the silicon-based nanotips.     

Luminescence of ZnS and ZnSe nanostructures in anodic aluminum oxide porous matrices

Investigations of the luminescent characteristics of ZnSe and ZnS nanostructures obtained by thermal deposition on porous anodic aluminum oxide films are presented. Luminescence associated with the interaction of semiconductors with the matrix material was detected.     

高质量多孔氧化铝模板的制备

在草酸电解液中研究了阳极氧化法制备多孔氧化铝模板(AAO模板)。采用场发射扫描电子显微镜对多孔模板的形貌进行表征,结果表明:模板孔的分布均匀有序,孔径在40~70 nm;电解液浓度、氧化电压、氧化温度和氧化时间都会影响模板的形态;不经过高温退火及抛光也可以制得规则排布的多孔AAO模板。X射线衍射分析表明:氧化铝膜的主要成分为非晶态Al2O3。     

Polarization properties of porous anodic alumina with Y-branched Cu nanowires

Porous anodic alumina (PAA) templates with branch structure are fabricated by the two-step anodic oxidation processes, and then the Y-branched Cu nanowires are synthesized in the templates using an alternating current (AC) deposition method. We observe the morphology image of the samples by scanning electron microscopy (SEM), and measure the transmission spectrum and the polarization spectrum of the samples by the spectrophotometer. The results show that PAA films with Y-branched Cu nanowires have better transmittance in the near infrared region. An extinction ratio of 15-18 dB and an insertion loss of 0.1-0.4 dB are obtained in this region. Therefore PAA with Y-branched Cu nanowires can be used as a near-infrared micropolarizer, and this kind of micropolarizer would have a promising future in the field of photoelectricity integration.     

高质量多孔氧化铝模板的制备

在草酸电解液中研究了阳极氧化法制备多孔氧化铝模板（AAO模板)。采用场发射扫描电子显微镜对多孔模板的形貌进行表征,结果表明：模板孔的分布均匀有序,孔径在40～70 nm;电解液浓度、氧化电压、氧化温度和氧化时间都会影响模板的形态;不经过高温退火及抛光也可以制得规则排布的多孔AAO模板。X射线衍射分析表明：氧化铝膜的主要成分为非晶态Al2O3/sub>。     

Photoluminescence identification of surface contaminants on zinc oxide from their phase transitions

The spectra of photoluminescence (PL) from a zinc oxide (ZnO) crystal included an unusual feature of an ultraviolet (UV) emission at a higher energy than the ZnO interband transitions. The energy of this UV emission varied with temperature and included two discontinuous energy steps in the temperature range from 78 to 700?K. The temperature values of the steps match phase transition temperatures of ethanol. Ethanol was used during sample cleaning and can be trapped in the form of nanoparticles inclusions. Both the intrinsic and defect site, PL signals have different temperature dependencies from those of bulk crystals, as seen during radioluminescence. The origins of the changes are discussed.     

Investigation of the lateral spread of erbium ions implanted in silicon crystal

The erbium ions at energy of 400 keV and dose of 5×10 15 ions/cm 2 were implanted into silicon single crystals at room temperature at the angles of 0,45 and 60.The lateral spread of 400 keV erbium ions implanted in silicon sample was measured by the Rutherford backscattering technique.The results show that the measured values were in good agreement with those obtained from the prediction of TRIM’98 (Transport of Ions in Matter) and SRIM2006 (Stopping and Range of Ions in Matter) codes.     

载铈纳米TiO2粉体的制备及其反射光谱特性研究

采用金属离子组装技术对纳米TiO2进行了稀土元素铈的负载,借助X射线衍射和透射电子显微镜对载铈纳米TiO2粉体进行了表征,并用紫外-可见光漫反射光谱法对载铈前后纳米TiO2粉体的反射光谱特性进行了分析。结果发现：稀土元素铈负载后,纳米TiO2的反射光谱特性向可见光方向移动,红移到了500nm;并且在可见光区域的吸光率也发生了明显变化,提高了3倍。表明稀土元素铈的负载有利于提高纳米锐钛矿型TiO2对可见光和紫外光的吸收,从而大幅度提高其光催化活性。     

双模自组织量子点光致发光的温度依赖性

采用稳态速率方程模型,对双模自组织量子点光致发光的温度依赖性进行了研究,模拟获得了不同温度下双模自组织量子点的光致发光光谱,并进一步研究了两组量子点分布的光致发光强度比的温度依赖性。研究表明:在低温下(<75K),两组量子点分布的发光强度比基本保持不变;随着温度的升高(75K相似文献   

多孔阳极氧化铝薄膜光学常数的确定

根据多孔阳极氧化铝(AAO)薄膜的实验透射谱(200—2500nm)，采用极值包络线算法确定其光学常数，并由此较精确地计算出AAO薄膜样品在该波段的光学常数.结果表明，多孔氧化铝薄膜表现出直接带隙(能隙约4．5eV)半导体的光学特性，且其光学常数与制样中的重要工艺参数阳极氧化电压有显著的相关性，即随阳极氧化电压的增加，AAO薄膜的厚度、折射率和光学能隙变大，消光系数减小．同时，计算得到的薄膜厚度与实测值相吻合，则说明计算结果和实验值是自洽的. 关键词： 薄膜光学 光学常数 多孔阳极氧化铝 阳极氧化电压     

Excitation and emission processes of Tb in porous anodic alumina

The strong photoluminescence (PL) of porous anodic alumina (PAA) with terbium deposition is reported. PAA, which has a regular pore morphology, is considered an effective template for fabricating luminescent composites. Tb was deposited onto PAA films by immersion in alcoholic solution with terbium chloride followed by heat treatment. The PL spectra demonstrate typical bands of Tb³⁺ corresponding to ⁵D₄ → ⁷F_j (j = 3, 4, 5, 6,) electron transition, with the maximum at 18,360 cm⁻¹ (⁵D₄ → ⁷F₅). The PL mechanism of Tb³⁺ was systematically studied with annealing temperature. The non-radiative relaxation channel is provided by OH hydroxyls at the surface of porous anodic alumina and, after annealing at 900 °C, the PL yield is highly improved. The PL intensity of Tb³⁺ increases with laser power and a saturation phenomenon, associated with the ratio of Tb³⁺ to Tb⁴⁺ ions, is observed at approximately 90 W/cm². Based on a theoretical model, the optical cross-section σ of terbium in PAA is estimated, with a value close to that of other porous materials doped with the rare-earth elements.     

Improved electrical properties of silicon-incorporated anodic niobium oxide formed on porous Nb-Si substrate

In the present study, porous Nb-Si alloy films with isolated nano-column morphology have been successfully developed by oblique angle magnetron sputtering on to aluminum substrate with concave cell structure. The deposited films are amorphous with the 15 at% silicon supersaturated into niobium. The porous Nb-15 at% Si films, as well as niobium films with similar morphology, are anodized at several voltages up to 50 V in 0.1 mol dm⁻³ ammonium pentaborate electrolyte. Due to the presence of sufficient gaps between neighboring columns, the gaps are not filled with anodic oxide, despite the large Pilling-Bedworth ratio (for instance, 2.6 for Nb/Nb₂O₅) and hence, a linear correlation between the reciprocal of capacitance and formation voltage is obtained for the Nb-15 at% Si. From the comparison with the anodic films formed on porous niobium films, it has been found that silicon addition improves the thermal stability of anodic niobium oxide; the change in capacitance and increase in leakage current become small for the Nb-Si. The findings indicate the potential of oblique angle deposition to tailor porous non-equilibrium niobium alloy films for high performance niobium-base capacitor.     

低能氩离子束对多孔铝阳极氧化膜表面的刻蚀效应研究

用低能氩离子束(Ar⁺)处理了多孔铝阳极氧化膜(AAO)表面.扫描电子显微镜和原 子力显微镜结果表明，Ar⁺束刻蚀不仅可以有效地去除AAO反面阻挡层，还可使A AO表面产生多种特殊的形貌，如采用倾角入射可使其表面产生波纹，倾角入射同时旋转样品 台，可实现表面抛光.并结合Bradley和Harper提出的无定形材料表面波纹的形成和演化理论 解释了AAO表面波纹的特征. 关键词： 多孔铝阳极氧化膜 离子束刻蚀     

基于蒙特卡洛方法的钛氧化物忆阻器辐射损伤研究

纳米钛氧化物忆阻器有望成为新一代阻性存储器基本单元并应用于辐射环境中的航天器控制及数据存储系统. 辐射能量, 强度, 方向, 持续时间等要素发生改变均可能对钛氧化物忆阻器受到的辐射损伤构成影响, 然而, 目前尚无相关具体研究. 基于以蒙特卡洛方法为核心的SRIM仿真, 本文针对宇宙射线主体组成部分——质子及 α射线定量研究了各个辐射要素与钛氧化物忆阻器辐射损伤的关联, 依据器件实测数据研究了辐射要素与导通阻抗, 截止阻抗及氧空缺迁移率等忆阻器主要参数的关系, 进一步利用SPICE仿真讨论了辐射对杂质漂移与隧道势垒共存特性的影响, 从而为评估及降低钛氧化物忆阻器辐射损伤, 提高器件应用于辐射环境的可靠性提供依据.     

Photoluminescence properties of heat-treated porous alumina films formed in oxalic acid

Photoluminescence and optical properties of as-anodized and heat-treated at 500 °C porous alumina films formed in a 0.3 M oxalic acid at 40 V have been studied. The FTIR indicates that the oxalate ions are embedded in the anodic alumina as chelating bidentate structures and further heating up to 500 °C does not cause any change in ion coordination. The results of time-resolved spectroscopy show the presence of two luminescence centers both in the as-anodized and heat-treated anodic alumina films with lifetimes of about 0.25 and 4.0 ns. The F⁺-centers in anodic alumina are responsible for the luminescence peak at about 420 nm, with a lifetime of about 4.0 ns. The luminescence peak at about 480 nm, with lifetime of about 0.25 ns, can be attributed to the luminescence of carboxylate ions existing in bulk of anodic alumina.     

The effect of annealing on the photoluminescent and optical properties of porous anodic alumina films formed in sulfamic acid

Photoluminescent and optical properties of porous oxide films formed by two-step aluminum anodization at a constant potential of 30 V in sulfamic acid have been investigated after their annealing, ranging from room temperature up to 600 °C. X-ray diffraction reveals the amorphous nature of porous oxide films. Infrared and energy dispersive spectroscopy indicates the presence of sulfuric species incorporated in oxide films during the anodization. Photoluminescence (PL) measurements show PL bands in the range from 320 to 600 nm. There are two peaks in emission and excitation spectra. One emission peak is at constant wavelength centered at 460 nm and the other shifts from 390 to 475 nm, depending on excitation wavelength. For excitation spectra, one spectral peak is at constant wavelength at 270 nm and the other also shifts to longer wavelengths while increasing emission wavelength. Upon annealing of the as-prepared oxide films PL increases reaching maximum value at about 300 °C and then decreases. The results indicate the existence of two PL centers, one placed at surface of the pore wall, while the other positioned inside the oxide films.     

A comparison of silicon oxide and nitride as host matrices on the photoluminescence from Er+ ions

This paper compares the properties of silicon oxide and nitride as host matrices for Er ions.Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system.After deposition,the films were implanted with Er3+ at different doses.Er-doped thermal grown silicon oxide films were prepared at the same time as references.Photoluminescence features of Er3+ were inspected systematically.It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe.However,a very high annealing temperature up to 1200° C is needed to optically activate Er3+,which may be the main obstacle to impede the application of Er-doped silicon nitride.