Estimation of density changes associated with growth in vacuum-deposited amorphous films of antimony

Amorphous antimony films consisting of separate islands were deposited onto SiO_x and GeO_x film substrates at room temperature in a vacuum of 10^-5 Torr. By comparison of the interferometrically determined thickness and the total mass of incident vapour determined with a quartz oscillator, it was found that a sudden change in film density occurs at a certain film thickness d₀. Another change in film density, which is gradual, occurs in the vicinity of a certain thickness $\text{d}{}_{\mathrm{<mtext>c</mtext>}}\text{(d}{}_{\mathrm{<mtext>c</mtext>}}\text{\&\#62; d}{}_{\mathrm{<mtext>0</mtext>}}\text{)}$. The change at d₀ is caused by the coalescence of neighbouring islands. The change at d_c, at which the coalescence of amorphous islands is almost completed, is associated with crystallization.     

Structure and electrical properties of vacuum-deposited antimony telluride thin films on an amorphous substrate

Sb₂Te₃ thin films, 50–109 nm thick, have been prepared by vacuum evaporation on to quartz substrates. Electrical properties of as-deposited and annealed films show that the activation energy is thickness dependent. Optical measurements indicate that there is an indirect transition having an energy of 1.9 eV. Transmission electron micrographs show the fine grains of the deposit.     

Crystallization of amorphous antimony films on silver films

The crystallization process in amorphous antimony films 70–330 Å thick evaporated onto silver films 10–150 Å thick which have previously been evaporated onto glass is directly observed through an optical microscope. The conditions under which the crystallization process in the amorphous antimony films is observed are found to be severely limited by the preparation conditions of the silver films. The crystallization can only be observed on silver films thinner than 30–40 Å which have previously been exposed to oxygen or nitrogen gas. The crystallization thickness of amorphous antimony films on these substrates is estimated to be 123-75 Å as the substrate temperature varies from 20 to 80 °C and the activation energy for crystallization to be 0.23-0.30 eV as the film thickness varies from infinity to 200 Å.     

Crystallization of amorphous antimony films

Diffusion of the divalent impurities Mn²⁺, Ca²⁺, Cu²⁺, Fe²⁺, Co²⁺, Pb²⁺, Zn²⁺, Eu²⁺ and S^2- in sodium chloride and other alkali halide crystals has been studied by electron microscopy and diffraction. At temperatures in the range 100°–700°C the impurities diffuse to the surface and form oxides which in some cases are epitaxial. This distribution of the impurities on the surface is studied and is found to have a strong influence on the overgrowth of other epitaxial deposits.     

Electrical resistivity of amorphous antimony trisulphide films

The electrical resistivity of amorphous antimony trisulphide films was investigated in the temperature range from 0 to 200° C. The temperature dependence of the resistivity follows the ordinary semiconducting behaviour above room temperature. The electrical band gap was found to be consistent with a mobility gap. By annealing the conductivity reduces and the slope of the conduction is increased indicating that the mobility gap is appreciably enhanced by annealing.     

一种富钛NiTi薄膜的晶化动力学

本实验采用直流磁控溅射法制备了一种非晶的富TiNiTi薄膜，其成分为Ni46.34%（原子分数），Ti53.66％（原子分数）。采用变温方法研究了这种非晶薄膜的晶化动力学。测得非晶薄膜晶化的激活能为271kJ/mol，平均Avrami指数为1．17。采用以上获得的动力学参数计算了薄膜在773K的等温晶化动力学曲线。计算结果与实验结果吻合较好。在薄膜的晶化过程中伴随着Ti2Ni的析出。     

Substrate effects on the crystallization kinetics of amorphous selenium thin films

A thermoanalytical technique has been used to study crystallization in thin amorphous selenium (a-Se) films deposited on polyimide and on aluminum-coated polyimide substrates. Through analysis of thermograms obtained by differential scanning calorimetry, the activation enthalpy of crystallization for a-Se on these substrates has been measured. It has been found that the film deposited on Al-coated polyimide crystallizes with an activation enthalpy similar to that obtained for bulk-quenched a-Se, while the film deposited on bare polyimide crystallizes with a lower activation enthalpy than that for the bulk sample. This suggests that the structure of a-Se films can be influenced by the choice of substrate.     

Size and temperature dependence of thermoelectric power and electrical resistivity of vacuum-deposited antimony thin films

Thin antimony films of thicknesses in the range 30 to 200 nm have been vacuum deposited on glass substrates at room temperature. After annealing for about an hour at 500 K, the thermoelectric power and electrical resistivity were measured in vacuum as a function of temperature. The thermoelectric power and electrical conductivity data were combined and simultaneously analysed using the effective mean free path theory of size effect in thin films developed by Tellier and Pichard et al. In addition, their temperature dependence was also analysed. It was found that the thermoelectric power is positive and increases with increasing temperature and is inversely proportional to the thickness of the film. The electrical resistivity was found to be temperature dependent with the temperature coefficient of resistivity being positive, and inversely proportional to the thickness of the film. Analysis combining the data from the thermoelectric power and electrical conductivity measurements has led to the determination of mean free path, carrier concentration, effective mass, Fermi energy and the parameter The data were analysed for least squares fitting by local functions, such as the spline functions, which eliminates possible errors in conventional least squares fitting of data using non-local functions valid throughout the range.     

Annealing and crystallization of amorphous germanium thin films

The isochronal and isothermal annealing of the room temperature electrical resistivity of vacuum-deposited a-e thin films was studied for different annealing temperatures up to about 500°C. By analysing the annealing kinetics, it is possible to show that the crystallization process can be characterized by a single activation energy of 3.5 eV and the nucleation process by an activation energy of 3 eV for different coating conditions. It is proposed that the crystal growth takes place by diffusion of extended divacancies to the crystalline-amorphous interface and by subsequent rearrangement of the relaxed atoms fit the crystalline matrix.     

非晶硅薄膜晶化过程的研究

多晶硅薄膜具有较高的电迁移率和稳定的光电性能,是制备微电子器件、薄膜晶体管、大面积平板液晶显示的优质材料.多晶硅薄膜被公认为是制备高效、低耗、最理想的薄膜太阳能电池的材料.因此,如何制备多晶硅薄膜是一个非常有意义的研究课题.固相法是制备多晶硅薄膜的一种常用方法,它是在高温退火的条件下,使非晶硅薄膜通过固相相变而成为多晶硅薄膜.本文采用固相法,利用X-ray衍射及拉曼光谱,对用不同方法制备的非晶硅薄膜的晶化过程进行了系统地研究.     

Growth and crystallization of amorphous antimony films obliquely deposited in a vacuum of 10-5 Pa

The growth and crystallization of amorohous antimony (a-Sb) films deposited onto collodion were studied as a function of the oblique angle Θ of the incident vapour beam with respect to the normal to the substrate surface by both electron and optical microscopies. The crystallization thickness increases gradually from 18 to 25 nm as Θ increases from 0° to 70° and jumps to 120–130 nm at Θ = 80° while the crystallinity of the crystallized film deteriorates as Θ increases. Crystallites grown in the a-Sb film retain a disk-like shape for normal deposition and a shape that is elongated perpendicularly to the vapour beam for oblique beam for oblique deposition. When Θ = 80° however, the film remains only partially crystallized even at a thickness of 120–130 nm and the crystallite shape is irregular. It is found that these phenomena are brought about not only by the characteristic growth of the obliquely deposited film but also probably by the adsorption of the residual gases on the internal surface developed in such a film.     

Properties of vacuum-deposited polyimide films

Vacuum-deposited polyimide (PI) thin films have been prepared by co-deposition of precursor pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) followed by thermal treatment. The dependency of the optical and electrical properties, chemical resistivity and mechanical stability on the composition (ODA:PMDA) and the degree of imidization of the PI layers have been investigated and discussed. The experimental results have yielded possibilities to microstructure the vacuum-deposited PI films by excimer laser irradiation or reactive ion etching in gas mixture CF₄/O₂.     

Room-temperature crystallization of amorphous films by RF plasma treatment

The crystallization of amorphous thin films was achieved by 13.56 MHz RF (radio frequency) plasma treatment. This crystallization process has a strong advantage that the sample temperature is lower than 120 °C during the plasma treatment even without compulsory cooling and various amorphous films are crystallized after 2 min or so. This treatment works on amorphous films of various materials, independently of the film preparation method and substrate materials. Crystallization has been confirmed on amorphous thin films of sputtered ITO (tin doped indium oxide) deposited on soda-lime glass and PET (polyethylene terephthalate), of sputtered TiO₂ on soda-lime glass, of sol-gel derived TiO₂ on silicon wafer and of sputtered hydrogen-doped silicon on soda-lime glass.The plasma gas pressure was found to be the key parameter in the plasma crystallization process. The appropriate gas pressure depends on the plasma gas species and not on film or substrate materials. A Cu electrode, attached to the backside of the substrate and is electrically floated from the electric ground, was found to enhance the plasma crystallization performance.     

膜厚对四面体非晶碳膜机械性能的影响

采用过滤阴极真空电弧技术以相同的工艺条件在p(100)单晶硅衬底上制备了不同厚度的四面体非晶碳薄膜,并利用表面轮廓仪测试薄膜的厚度和应力,利用纳米压入仪测试薄膜的硬度、杨氏模量和临界刮擦载荷.试验表明,在一定的扫描波形条件下,薄膜大约以0.7 nm/s的沉积速率稳定生长.随着膜厚的增加,薄膜的应力持续降低,当膜厚超过30nm时,应力将低于5GPa;当膜厚超过300nm时,硬度和杨氏模量分别将近70GPa和750GPa,已经十分接近体金刚石的性能指标.另外,随着膜厚增加所产生的应力变化,也导致了可见光拉曼光谱非对称宽峰的峰位逐渐向低频偏移.