N2 Protection Research Articles

Aluminum-Induced Crystallization of PECVD Amorphous Silicon

ABSTRACTAluminum-induced crystallization (AIC) of amorphous silicon (a-Si) in a conventional furnace with N2 protection has been studied at reaction temperatures ranging from 200 to 500°C by using optical microscopy, and transmission and scanning electron microscopy. The a-Si and Al layers were deposited with plasma-enhanced chemical vapor deposition (PECVD) and electron beam evaporation, respectively. The structures in the study are Al/a-Si and a-Si/Al on Si or glass wafers coated with 3000 Å PECVD SiO2. It was found that Al induces crystallization of a-Si for both Al/a-Si and a-Si/Al structures by exchanging positions of Al and Si layer through diffusion of Si into Al and the grain size of crystallized Si (c-Si) increases with the decrease of AIC temperature. AIC for Al/a-Si structures starts at a temperature as low as 200°C, which is 100°C lower than that for a-Si/Al structures. Kinetics analysis found that the activation energies are 1.76 eV and 1.65 eV for both Al/a-Si and a-Si/Al structures, respectively. The quality of AIC c-Si depends on the order, thickness and thickness ratio of a-Si to Al. Microstructural observations indicated that the c-Si for Al/a-Si structures is better and more suitable for use in fabrication of thin film transistors (TFTs) than that for a-Si/Al structures.

Effects of heat treatment process on thin film alloy resistance and its stability

Alloy thin film for advanced pressure sensors was manufactured by means of ion-beam sputtering SiO2 insulation film and NiCr thin film on the 17-4PH stainless steel elastic substrate. The thin film resistance was respectively heat-treated by four processes. The effects on stability of thin film alloy resistance were investigated, and paramaters of heat treatment that make thin film resistance stable were obtained. The experimental result indicates that the most stable thin film resistance can be obtained when it is heat-treated under protection of SiO2 and N2 at 673 K for 1 h, and then kept at 473 K for 24 h. Pressure sensor chips of high precision for harsh environments can be manufactured by this process.

Phase behavior of supercritical CO2/Styrene/Poly(ethylene terephthlate) (PET) system and preparation of polystyrene/PET composites

Phase behavior of supercritical CO2/styrene/poly (ethylene terephthlate) (PET) system was determined at 35°C and different pressures. The concentration of styrene in the fluid phase ranged from 0 to 1.3mol/l. Styrene partitioned between the fluid phase and PET films, and significant amount of styrene was absorbed into PET matrix. When the styrene contained 0.3mol% initiator azobis (isobutyronitrile) (AIBN), the mass uptake was higher than that of the styrene without the initiator because the AIBN initiated polymerization during the soaking period. It was found that considerable amount of styrene was carried out by CO2 in the depressurization process. After the depressurization process, the PET films impregnated with styrene and AIBN were placed in a reactor and heated at 80°C for 4h under the protection of N2, and the PET/Polystyrene (PS) blends were obtained. The properties of the blends could be controlled by manipulating experimental conditions, such as soaking time, pressure and styrene concentration. The blends were characterized using IR, SEM, rheological measurement, and some mechanical properties were also determined. Rheometer study indicates that the presence of PS in PET can improve the mobility of PET.

Composite laminate veneers with a continuous inorganic phase comprising microporous sintered glass fiber networks.

Veneers were made from sheets consisting of a three-dimensional network of sintered ultrafine glass fibers. The sheets were molded by a vacuum-pressure technique and then impregnated with a liquid resin. Impregnation was performed with a method that enabled the depth of penetration to be monitored. The resin was cured with UV radiation under N2 protection. By the use of TiO2-containing resins the veneer achieved an enamel-like appearance. An in vitro toothbrush dentifrice abrasion test showed a high wear resistance and persisting surface luster. Scanning electron and light microscopy showed fairly smooth and flat light-reflecting glass structures in the surface.

Vereinfachte titrimetrische Halbmikrobestimmung der Lipase im Serum

The quantitative, titrimetric and kinetic method for the determination of lipase in serum, duodenal juice and punctures by Rick (Rick, W. (1969), this journal 7,530-539) has been adapted as a routine semimicro-method using 0.20 ml volume of spcimen without N2 protection. The description of the procedure and quality control data are reported. The method has been checked for more than 3 years and sera from more than 3000 patients have been investigated.