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300℃.

Fabricating nano-Si by LICVD, we discover: there is a low threshold of laser intensity and a high threshold of SiH 4 flow speed, a nd they are positively correlated to maintain the high temperature for SiH 4 to split. In order to obtain small and even nano-Si particles, the laser intensit y must be large and the SiH 4 flow speed must be fast correspondingly to increa se the nucleation rate of nano-Si particles, and reduce the numbers of Si atoms absorbed by each nano-Si nucleus, and shorten the growth period of ea ch nano-Si nucleus. When nano-Si is annealed for dehydrogeniza tion after it is prepared, its IR absorption spectrum is changed. The positionintensities and shapes of four characteristic absorption spectrum bands are changed respectively,becaus enanoSisurface is large and oxidized so that its constituent is changed.In order to weaken such oxidation,nanoSi should be annealed in Ar but not in the air,and the annealing temperature should be lower than300℃.