Ag-SiO_2复合薄膜形貌和吸收特性的研究

Morphology and absorption properties of Ag-SiO_2 composite films

通过分层镀膜的方式制备Ag和SiO2的分层结构,经过快速热退火后,Ag颗粒扩散到复合薄膜的表面附近.通过改变Ag颗粒扩散的距离(SiO2的膜厚),可很好地控制Ag颗粒在复合薄膜表面附近的大小,浓度和形貌,进而对共振吸收特性产生影响.在实验中,根据Ag颗粒扩散的长度来调节退火的时间.发现经过足够长的时间(17.5min)后,Ag颗粒会形成平行于衬底的平面团簇.由于Ag原子在平面团簇之间容易扩散,使得Ag颗粒的粒径平均值变小并趋于某一特定的半径,且粒径分布范围变小,导致吸收谱发生蓝移,吸收带变窄,且强度增加.

Ag/SiO2 multilayers were prepared by RF magnetron sputtering. Via rapid thermal treatment, most of Ag nanoparticles move up to the surface. By changing the layer thickness of Ag and SiO2, Ag particles of different size, density and shape were obtained. The effect of factors such as size, density and shape of the Ag particle, on resonance absorption is also investigated. We change the annealing time according to the diffusion length. Ag particles with a facet parallel to substrate are obtained under adequate annealing time （ 17.5 min）. Since the atoms easily transport between particles within the facets, the radius of Ag particle decreases, and tends to a critical size. Correspondingly, the resonance absorption band becomes narrower and blueshift OCCULTS.