硅基微纳结构薄膜中全向光吸收效应

Omnidirectional Optical Absorption Effect in a Microstructure Silicon Thin Film

研究了一种由硅基光子晶体与金属复合微纳结构薄膜中的全向光吸收效应。与完整的硅/金属复合薄膜进行比较研究发现,在硅薄膜厚度相同的条件下硅基微纳结构薄膜能够使吸光度提高近70%。此外,结果显示这种光吸收增强效应对入射角度的变化不敏感。在以0°~60°角度入射的情况下,硅微纳结构薄膜都能够具备接近100%的光吸收。通过对能带以及场构型分析可以发现,这种现象产生的原因归结于金属平板与截断光子晶体中特殊的边界陷光效应和六角晶格的全向带隙。

Omnidirectional optical absorption of a microstructure film composed of a metallic film combined with a silicon-based photonic crystal is investigated theoretically.Compared with the intact silicon/metal composite films,the siliconbased microstructure films can increase the absorbance by nearly 70% under the same silicon film thickness.In addition,the results show that this optical absorption enhancement effect is insensitive to changes in the incident angle.In the case of 0°-60°angle of the incident,the silicon microstructure film can have nearly 100% of the light absorption.By analyzing the corresponding bandgap and field distribution,it is found that the reason of this phenomenon is attributed to the special boundary trapping effect and the omnidirectional bandgap of hexagonal lattice.