Comparative study on dry etching of polycrystalline diamond thin films

The reactive ion etching (RIE) technique was used to etch polycrystalline diamond thin films. In this study we investigate the influence of process parameters (total pressure, rf power, gas composition) of standard capacitively coupled plasma RIE system on the etching rate of diamond films. The surface morphology of etched diamond films was characterized by Scanning Electron Microscopy and the chemical composition of the etched film part was investigated by Raman Spectroscopy.We found that the gas composition had a crucial effect on the diamond film morphology. The use of CF₄ gas resulted in flatter surfaces and lateral-like etching, while the use of pure O₂ gas resulted in needle-like structures. Addition of argon to the reactant precursors increased the ion bombardment, which in turn increased the formation of non-diamond phases. Next, increasing the rf power from 100 to 500 W increased the etching rate from 5.4 to 8.6 μm/h. In contrast to this observation, the rise of process pressure from 80 to 150 mTorr lowered the etching rate from 5.6 down to 3.6 μm/h.     

前驱体凝胶法制备SrxBa1-xNb2O6铁电薄膜的研究

以羟基羧酸作为配位剂与金属离子配位,以乙二醇为交联剂促进聚合反应并以碳酸盐为反应原料,采用前躯体凝胶法在水溶液中制备铌酸锶钡(SrxBa1-xNb2O6,SBN)前驱体溶胶.将此溶胶在预热的Si/SiO2/Ti/Pt基片上旋转涂膜得到了平整均匀的SBN铁电薄膜.研究了pH值、乙二醇(EG)/柠檬酸(CA)(质量比)、热处理温度对SBN凝胶相组成、相结构以及SBN薄膜形貌的影响规律.结果表明当pH≥7且EG:CA=60:40时,可以获得稳定性良好的溶胶.对SBN薄膜热处理和红外光谱分析表明:随温度升高,SBN相衍射峰逐渐增强,晶型转变明显.同时COO-基团也逐渐消失,Sr-O、Ba-O和Nb-O峰显著增强.在800℃时,可得到单一钨青铜相的铌酸锶钡;SBN薄膜的SEM微观组织表明在750℃退火条件下可以获得晶粒为纳米级的表面均匀、无裂纹的SBN薄膜.     

172 nm excimer VUV-triggered photodegradation and micropatterning of aminosilane films

Emission from Xe₂* excimers exhibiting photon energies between 7 and 10 eV can be used to induce strong surface modification effects on polymeric materials in the top 100 nm layer. In order to identify suitable monomers for this VUV-based process, the photodegradation mechanism of different organosilanes of the general structure R-CH₂-Si(OCH₃)₃ was elucidated by quantum chemical calculations. Herein, the photodegradation of 3-aminopropyltrimethoxysilane films by the use of a 172 nm excimer lamp under different irradiation conditions is described and completed by micropatterning experiments. The presence of 1000-5000 ppm oxygen was found to promote the transformation process to an inorganic-like surface. The films obtained were analyzed by X-ray photoelectron spectroscopy, contact angle measurements and fluorescence microscopy after covalent attachment of a fluorescent dye to the remaining amino groups. Complementary, silver staining was used to visualize photopatterning.     

Properties of thin TiN films deposited onto stainless steel by an in-line dry coating process

A new coil-coating pilot plant, capable of utilizing ion plating, sputtering and plasma-assisted chemical vapor deposition (PACVD) processes, independently or in series, was developed and optimum conditions for TiN, TiC, Al_xO_y, SiO_x and Cr coating were established. This paper is mostly concerned with the results of characterization (conducted in parallel by the authors′ two institutions) of TiN films deposited by ion plating or sputtering onto type-304 stainless steel strips. In particular, the dependence of the basic properties such as chemical composition, structure, adhesion, and color on the coating process are discussed with respect to anti-corrosion, anti-wear, and decorative applications. TiN coatings with a very attractive gold coloration were obtained; they performed well in wear testing, but did not show satisfactory corrosion resistance. However, it was found that the latter can be improved significantly by depositing a SiO_x, top layer by PACVD above the TiN coating. Thus the in-line dry coating processes are capable of producing highly functional steel surfaces with decorative color and high corrosion resistance.     

新型纳米功能材料

讨论了纳米材料复合薄膜的结构和特性,涉及到与力学、防护、电池等特性有关的结构,重点分析了电学、光学、光电特性,如新型纳米线复合光电池,氧化锌(ZnO)纳米棒阵列的结构和荧光发射,以及金属纳米线阵列的制备和场发射特性.金属纳米线阵列场发射的高分辨,结构完美,工艺简单和极低的成本,有可能是未来平板显示器的重要组件.     

Magnetite thin films

A low temperature process for converting hematite (α-Fe2O3) thin films into magnetite (Fe3O4is described. The films produced are unambiguously identified as magnetite by several complementary methods of analysis. These include α-backscattering spectrography, X-ray powder diffractometry, and observations of electrical, magnetic, and optical properties.     

先驱硼薄膜的质量对MgB2超导薄膜的影响

以高纯乙硼烷(B2H6)为B源,采用化学气相沉积(CVD)方法在多晶Al2O3衬底上沉积B薄膜,然后在Mg蒸气中异位退火来制备MgB2超导薄膜.通过X射线衍射和MgB2超导薄膜的电阻-温度曲线,研究了先驱硼薄膜的质量对MgB2超导薄膜的影响.     

Phase-selective synthesis of a silicoaluminophosphate molecular sieve from dry gels

Silicoaluminophosphate (SAPO) molecular sieves with AFI and CHA structures have been synthesized from a reaction mixture containing triethylamine (TEA) as a template or structure-directing agent. The syntheses were carried out at 180-200 °C for several days both from dry gels (dry gel conversion) and homogeneous gels (conventional electric heating). From similar reaction mixtures, SAPO-5 (AFI structure) and SAPO-34 (CHA structure) molecular sieves are phase-selectively obtained from dry gel conversion and conventional electric heating, respectively. The phase-selectivity may be explained by the slow crystallization of the dry gel conversion due to low water or TEA concentration under the reaction conditions and the difference of the relative stability of SAPOs (AFI < CHA) under hydrothermal conditions. This phase-selective synthesis with dry gel conversion may lead to a new method for the synthesis of relatively unstable molecular sieves (having large pores) such as VFI or VPI-5.     

Metal-doped magnetite thin films

This paper investigates magnetite (Fe3O4) thin film containing a small amount of a metal element. The films are prepared by rf sputtering with a composite target of ceramic iron oxide with metal chips. Low-temperature magnetization of magnetite containing 5.3%Ge reveals that the film contains some magnetically weak coupling grains. The metal element Mg reduces both hematite (alpha-Fe2O3) and magnetite, resulting in single-phase wüstite (Fe1-xO). In contrast, adding Ge selectively reduces hematite, while magnetite remains unreactive. According to the free energy of reaction, the element Ge is able to reduce hematite only, whereas the element Mg is capable of reducing both hematite and magnetite. This property is in good agreement with the experiment results.     

High-Tc superconducting thin films

This review describes recent advances in thin film studies of high-T_c superconducting cuprates. Emphasis is placed on epitaxial thin film growth technologies for LnBa₂Cu₃O_x (Ln = Y, Eu) cuprates, and on microwave device applications. An exciting area of this research involves epitaxial multilayer structures, such as a superconductor/insulator/superconductor (SIS) combination, and so preliminary results on SIS fabrication are also described.     

Microporosity in thin films

Because a large number of vacancies and voids can be incorporated into thin films during the deposition processes the films are generally porous. The presence of excess vacancies and voids greatly influences the physical properties. In particular freshly deposited films contain a large number (up to 1%) of excess vacancies which are highly mobile at ambient temperature. These excess vacancies are readily annihilated by diffusing to various sinks available in the thin films. During the annihilation process some film properties, which are sensitive to variations in the vacancy concentration, change continuously with time until all the excess vacancies are eliminated, leading to an aging phenomenon. In this report thin film microporosity is described in terms of the vacancies and voids incorporated during the deposition processes. The origins of these vacancies and voids and their effects on the physical properties of thin films are also discussed.     

Application of semiconducting thin films

Semiconducting thin films are sub-divided into three groups, in order of decreasing degree of structural perfection, i.e. homoepitaxial, heteroepitaxial and polycrystalline films. The intricate way in which vital electrical parameters, especially in polycrystalline films, depend on processing is discussed. Problems of reproducibility and stability are shown to be major stumbling blocks which hamper widespread industrial applications. It is expected that future applications of polycrystalline semiconducting thin films will be largely restricted to devices in which thin film geometry is essential, which do not require tight control of electrical parameters, and which cannot possibly be realised in silicon.