By direct observations of transmission electron microscopy (TEM), irreversible morphological transformations of as-deposited amorphous Au/Si multilayer (a-Au/a-Si) were observed on heating. The well arrayed sequence o...By direct observations of transmission electron microscopy (TEM), irreversible morphological transformations of as-deposited amorphous Au/Si multilayer (a-Au/a-Si) were observed on heating. The well arrayed sequence of the multilayer changed to zigzag layered structure at 478 K (=Tzig). Finally, the zigzag structure transformed to Au nanoparticles at 508 K. The distribution of the Au nanoparticles was random within the thin film. In situ X-ray diffraction during heating can clarify partial crystallization Si (c-Si) in the multilayer at 450 K (= ), which corresponds to metal induced crystallization (MIC) from amorphous Si (a-Si) accompanying by Au diffusion. On further heating, a-Au started to crystallize at around 480 K (=Tc) and gradually grew up to 3.2 nm in radius, although the volume of c-Si was almost constant. Continuous heating caused crystal Au (c-Au) melting into liquid AuSi (l-AuSi) at 600 K (= ), which was lower than bulk eutectic temperature ( ). Due to the AuSi eutectic effect, reversible phase transition between liquid and solid occurred once temperature is larger than . Proportionally to the maximum temperatures at each cycles (673, 873 and 1073 K), both and Au crystallization temperature approaches to . Using a thermodynamic theory of the nanoparticle formation in the eutectic system, the relationship between and the nanoparticle size is explained.展开更多
Electric resistivity measurements and X-ray diffraction analysis were performed to study the isothermal phase transformation in amorphous Au-Si ribbons with eutectic composition pre- pared using melt-spinning techniqu...Electric resistivity measurements and X-ray diffraction analysis were performed to study the isothermal phase transformation in amorphous Au-Si ribbons with eutectic composition pre- pared using melt-spinning technique.A series of phase transformations take place spontaneously at room temperature and accelerate at elevated temperatures.Four stages of the transformation from amorphous state to the equilibrium state can be distinguished.Dis- cussion on the structural character of the metastable phases indicates that Hume-Rothery electron compounds and size factor compounds could form during isothermal aging.展开更多
The silicon epitaxial wafter for X band double Read-type DDR IMPATT diodes has been fabricatedby normal-low pressure growth technique. The hyperabrupt impurity profile and very thin p-layer, n-layerwere achieved.
文摘By direct observations of transmission electron microscopy (TEM), irreversible morphological transformations of as-deposited amorphous Au/Si multilayer (a-Au/a-Si) were observed on heating. The well arrayed sequence of the multilayer changed to zigzag layered structure at 478 K (=Tzig). Finally, the zigzag structure transformed to Au nanoparticles at 508 K. The distribution of the Au nanoparticles was random within the thin film. In situ X-ray diffraction during heating can clarify partial crystallization Si (c-Si) in the multilayer at 450 K (= ), which corresponds to metal induced crystallization (MIC) from amorphous Si (a-Si) accompanying by Au diffusion. On further heating, a-Au started to crystallize at around 480 K (=Tc) and gradually grew up to 3.2 nm in radius, although the volume of c-Si was almost constant. Continuous heating caused crystal Au (c-Au) melting into liquid AuSi (l-AuSi) at 600 K (= ), which was lower than bulk eutectic temperature ( ). Due to the AuSi eutectic effect, reversible phase transition between liquid and solid occurred once temperature is larger than . Proportionally to the maximum temperatures at each cycles (673, 873 and 1073 K), both and Au crystallization temperature approaches to . Using a thermodynamic theory of the nanoparticle formation in the eutectic system, the relationship between and the nanoparticle size is explained.
文摘Electric resistivity measurements and X-ray diffraction analysis were performed to study the isothermal phase transformation in amorphous Au-Si ribbons with eutectic composition pre- pared using melt-spinning technique.A series of phase transformations take place spontaneously at room temperature and accelerate at elevated temperatures.Four stages of the transformation from amorphous state to the equilibrium state can be distinguished.Dis- cussion on the structural character of the metastable phases indicates that Hume-Rothery electron compounds and size factor compounds could form during isothermal aging.
文摘The silicon epitaxial wafter for X band double Read-type DDR IMPATT diodes has been fabricatedby normal-low pressure growth technique. The hyperabrupt impurity profile and very thin p-layer, n-layerwere achieved.
基金supported in part by the National S&T Major Project of China under Grant 2011ZX02507-003in part by the Major State Basic Research Development Program of China(973 Program)under Grant 2011CB309501in part by the National High-Tech R&D Program of China(863 Program)under Contract 2012AA040402~~
