从制备过程、结构表征和物理性能三个方面对激光诱导化学气相沉积(LICVD)纳米硅和纳米氮化硅进行了比较系统的研究,获得了一系列有意义的结果。 选择适当的制备工艺参数可以制得不同粒径的纳米硅和纳米氮化硅,粒度分布比较均匀。纳米硅是结晶的,粒度为14～100nm。纳米氮化硅是非晶的,粒度为7～18nm。利用光学二步法能够制备高纯的理想化学计量的纳米氮化硅粉末(Si59.80wt％,N39.49wt％,O0.69wt％),N/Si高达1.321,非常接近于理想值(1.333)。 纳米硅具有类似于c-Si的晶格和键合结构,存在Si—Si、Si—H、Si—O—Si、Si—OH等键和硅悬挂键(Si_3Si~0)。纳米氮化硅具有短程有序结构特征(SiN_4),并且存在Si—N、Si—Si、Si—H、N—H、Si—O—Si和Si—OH等键和硅悬键(N_3Si~0)。 纳米硅具有不同于c-Si和a-Si的介电特性,提出了界面极化对介电特性起着主要贡献的模型,解释了在低频端具有很大的介电常数。首次发现nc-Si粒子光学吸收特性发生显著变化的临界尺寸(粒径)为～30nm,小于该粒径时其光学带隙明显加宽;粒度为15nm时,出现明显的吸收峰(5.77eV、4.28eV、3.46eV)。 首次发现纳米氮化硅具有强压电性和介电性。界面极化在介电特性中起着主导作用,使得纳米氮化硅呈现出许多奇异的新特性。对纳米氮化硅介电特性的应 Laser-induced chemical vapor deposition (LICVD) nanosilica and nanosilica have been systematically studied from three aspects of preparation process, structure characterization and physical properties, and a series of meaningful results have been obtained. Select the appropriate preparation process parameters can be made of different particle size of nano-silicon and silicon nitride, particle size distribution is more uniform. Nanosilica is crystalline, particle size of 14 ~ 100nm. Nano-silicon nitride is amorphous, with a particle size of 7 ~ 18nm. Highly pure, ideally stoichiometric nanosilica powder (Si59.80 wt%, N39.49 wt%, 0.69 wt%) can be prepared by optical two-step method with N / Si as high as 1.321, which is very close to the ideal value (1.333) . Nanocrystalline silicon has a lattice and bonding structure similar to c-Si, and there are bonds such as Si-Si, Si-H, Si-O-Si and Si-OH and silicon dangling bonds (Si 3 Si 0). The nano-silicon nitride has the characteristics of short-range ordered structure (SiN_4), and the presence of Si-N, Si-Si, Si-H, N-H, Si-O-Si and Si- 0). Nanosilica has dielectric properties different from those of c-Si and a-Si, and proposes a model of interface polarization that makes a major contribution to the dielectric properties, explaining that there is a large dielectric constant at the low frequency end. For the first time, the critical size (particle size) of the optical absorption of nc-Si particles was found to be ~ 30nm. The optical bandgap was obviously broadened when the optical absorption of nc-Si particles was smaller than 5.30eV, 4.28 eV, 3.46 eV). For the first time found that nano-silicon nitride has strong piezoelectric and dielectric properties. Interface polarization plays a leading role in the dielectric properties, making the nano-silicon nitride presents many strange new features. Application of Dielectric Properties of Nano - silicon Nitride