含氢非晶碳膜(a-C:H)红外光学特性的研究

采用端部霍尔离子源在硅基底上制备了含氢非晶碳膜（a-C:H）,并测量了4 000~1 500 cm-1的红外透射光谱。基于单层薄膜的透射关系,获得了仅有六个拟合参数的光学常数计算模型。利用该模型,可以同时获得薄膜在宽波段范围内的光学常数和厚度:折射率的最大值为1.94,消光系数的最大值为0.014 9,拟合薄膜厚度为617 nm 。     

Luminescence hydrogenated nanoamorphous Si films fabricated by reactive pulsed laser ablation

Hydrogenated nanoamorphous Si (na-Si:H) films have been fabricated by reactive pulsed laser ablation technique with hydrogen as reactive gas. It is found that the hydrogen pressure has a great effect on both the structure and photoluminescence (PL) properties of the films. Increasing the hydrogen pressure leads to a structural transition of the films from amphorous Si to na-Si:H, and the PL center wavelength of the na-Si:H films is varied with the hydrogen pressure. The PL decay times of the na-Si:H films are in the nanosecond scale and are shorter on the high energy side of their PL spectrum. The results demonstrate that the na-Si:H films are promising candidates for visible, tunable and high-performance light-emitting devices.     

Low energy proton beams from laser-generated plasma

Low energy proton beams are produced by ns pulsed Nd:Yag laser operating in repetition rate at intensities of the order of 10¹⁰ W/cm². Laser pulses interacting with thick and thin solid hydrogenated targets, placed in high vacuum, produce non-equilibrium plasmas with ion emission in backward and forward directions along the normal to the target surface.The ion emission is analyzed with time-of-flight techniques by using ion collectors and ion deflecting spectrometers. The spectra analysis permits the evaluation of the plasma temperature, density, proton energy and current, ion energy and charge state distributions.Special targets, based on thin polymers coupled to metals or to conducting nanostructures, induce high electric field in the plasma and confer high kinetic energy to the protons, up to about 200 eV.By using a post-acceleration system, placed along the target normal direction, it is possible to accelerate further the protons up to the energy depending on the applied acceleration voltage. The maximum proton energy of 30 keV, the current density of about10 nA/cm² and the beam quality can be improved, as discussed.     

Al诱导a-Si:H薄膜的晶化

采用等离子体化学气相沉积方法在镀Al玻璃及单晶Si衬底上制备了氢化非晶硅(a-Si:H)薄膜,研究了样品在不同的热处理过程中Al对其晶化过程的影响.X射线衍射测量发现,由于Al的存在使a-Si:H的晶化温度大幅度降低,并得到了有强烈(111)结晶取向的多晶Si薄膜.X射线光电子能谱分析表明,热处理过程中Al向Si薄膜表面的扩散降低了Si的成核温度.     

硫化氢对氢化丁腈橡胶性能的影响

就硫化氢与丁腈橡胶和氢化丁腈橡胶的不饱和双键,以及与丙烯腈侧基的老化反应的机理作了介绍。研究表明:氢化丁腈橡胶具有优异的耐硫化氢性能,适合用来生产石油钻探领域的相关橡胶制品。     

Kinetics of Isothermal Crystallization of Hydrogenated Castor Oil-in-Water Emulsions

Kinetics of isothermal crystallization of hydrogenated castor oil in water emulsions exhibiting multiple crystal morphologies have been studied experimentally by DSC and polarized light microscopy. The induction time of nucleation increases with the increase of the isothermal temperature under which crystallization occurred. Crystal growth has been observed by microscopy showing that both crystal morphologies, fibers and rosettes, grow linearly at the initial stage of crystallization and then slow down to reach a plateau value. The Avrami model, which has been widely used in kinetics studies of triacylglycerol systems, was employed to fit experimental results at different isothermal temperatures. It was found that experimental trends could be captured by introducing the volume fraction of each type of morphology into three-dimensional and one-dimensional full Avrami models.     

I-V characteristics of a-Si-c-Si hetero-junction diodes made by hot wire CVD

p-Type hydrogenated amorphous silicon (a-Si:H) was deposited on n-type crystalline silicon (c-Si) substrates to obtain hetero-junction diodes. Additionally, a thin intrinsic a-Si:H layer was inserted between both the p-type film and the n-type substrate to study its passivation effect on the c-Si surface. The amorphous films were obtained by the hot wire chemical vapor deposition (HWCVD) technique, using a tungsten filament and silane (SiH₄), hydrogen (H₂) and diborane (B₂H₆) gases, where the deposition parameters such as gas flow, substrate temperature and filament temperature were varied. Optical band gap, deposition rate and conductivity were measured for all the films. We studied the influence of the quality of the amorphous films upon the performance of the hetero-junction diodes. In particular, the diode ideality factor (n) and the saturation current density (J₀) were determined by measuring the current-voltage characteristics in dark conditions. It is shown that the presence of the intrinsic layer is fundamental for making good diodes, since devices made without this film cause the diodes to have high saturation current density and ideality factor (J₀>10×10⁻⁶ A/cm², n>4) as compared to diodes with a good intrinsic layer (J₀=5×10⁻⁹ A/cm², n=1.39). The results obtained are encouraging, but the quality of the intrinsic films still should be improved for applying them to HIT solar cells.     

High-rate deposition of hydrogenated amorphous silicon films using inductively coupled silane plasma

Inductively coupled plasma (ICP) generated at 13.56 MHz has been employed for high-rate deposition of device-quality hydrogenated amorphous silicon (a-Si:H). It has been shown that an increase in the flow rate of a monosilane gas enhances the generation rate of deposition precursors, while the ion flux decreases and becomes saturated. The defect density reaches the minimum at a deposition rate of 2.3 nm/s. It has also been demonstrated that even at deposition rates around 4 nm/s, a-Si:H deposited at 150°C exhibits a subgap defect density lower than 6×10¹⁶ cm⁻³ after 12 h AM1 (100 mW/cm²) light soaking.     

热壁加氢反应器运行过程中的材质劣化问题

堆焊层的表面开裂、氢致剥离，器壁母材的回火脆化、氢脆和氢致裂纹扩展等材质劣化问题是影响热壁加氢反应器使用安全的主要问题。对这些问题产生的原因及其影响因素作了概要的分析和讨论。并在理论分析和实验研究的基础上，探讨了热壁加氢反应器安全运行的保障技术。     

Role of argon in hot wire chemical vapor deposition of hydrogenated nanocrystalline silicon thin films

Structural, optical and electrical properties of hydrogenated nanocrystalline silicon (nc-Si:H) films, deposited from silane (SiH₄) and argon (Ar) gas mixture without hydrogen by hot wire chemical vapor deposition (HW-CVD) method were investigated. Film properties are carefully and systematically studied as a function of argon dilution of silane (R_Ar). We observed that the deposition rate is much higher (4-23 Å/s) compared to conventional plasma enhanced chemical vapor deposited nc-Si:H films using Ar dilution of silane (0.5-0.83 Å/s). Characterization of these films with Raman spectroscopy revealed that Ar dilution of silane in HW-CVD endorses the growth of crystallinity and structural order in the nc-Si:H films. The Fourier transform infrared spectroscopic analysis showed that with increasing Ar dilution, the hydrogen bonding in the films shifts from di-hydrogen (Si-H₂) and (Si-H₂)_n complexes to mono-hydrogen (Si-H) bounded species. The hydrogen content in the films increases with increasing Ar dilution and was found to be < 4 at.% over the entire range of Ar dilutions of silane studied. However, the band gap shows decreasing trend with increase in Ar dilution of silane and it has been attributed to the decrease in the percentage of the amorphous phase in the film. The microstructure parameter was found to be > 0.4 for the films deposited at low Ar dilution of silane and ~ 0.1 or even less for the films deposited at higher Ar dilution, suggesting that there is an enhancement of structural order and homogeneity in the film. From the present study it has been concluded that the Ar dilution of silane is a key process parameter to induce the crystallinity and to improve the structural ordering in the nc-Si:H films deposited by the HW-CVD method.