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用激光诱导化学汽相沉积 (LICVD)法制备纳米硅 ,发现 :激光强度存在低限阈值 ,SiH4的流速存在着高限阈值 ,二者正相关 ,以维持SiH4 裂解所需的高温。为了使纳米硅粒小而均匀 ,应加大激光强度 ,并相应加快SiH4 的流速 ,以提高纳米硅粒的成核率 ,减少每一个纳米硅核所吸收的硅原子数 ,并缩短每一个纳米硅核的生长期。纳米硅制取后退火脱H ,纳米硅的红外吸收光谱发生变化 :4条特征吸收带的位置、强度和形状各有改变。这是因为纳米硅的表面积很大 ,表面氧化使组态改变。为了减轻这样的氧化 ,纳米硅应在Ar气氛中而不是在空气中退火 ,并且开始退火的温度低于 30 0℃。
The laser induced chemical vapor deposition (LICVD) method was used to prepare nanosilica. The results showed that there was a low threshold of laser intensity and a high threshold of SiH4 flow rate, both of which were positively correlated to maintain the high temperature required for SiH4 cracking. In order to make the nano-silicon particles small and uniform, should increase the laser intensity, and accordingly to speed up the SiH4 flow rate in order to improve the nucleation rate of nano-silicon particles to reduce the number of silicon atoms absorbed by each nano-silicon core, and shorten each nano Silicon nuclear growth period. After the nanosized silicon was annealed off H, the infrared absorption spectrum of nanosilica changed: the position, intensity and shape of the four characteristic absorption bands changed. This is because the surface area of nano-silicon is very large and the surface oxidation changes the configuration. In order to mitigate such oxidation, the nanosilica should be annealed in an Ar atmosphere rather than in air, and the temperature at which the anneal begins is below 300 ° C.