Research On Optical Characteristics Of Multi-configuration Nanostructure Arrays Based On FDTD Method

Under certain conditions, multi-configuration nanostructure arrays can show somespecial optical effects, such as Antireflection effect, Extraordinary Optical Transmissionand Surface-Enhanced Raman Scattering. All of these extraordinary effects ensure thatthese nanostructure arrays could be applied in various fields, particularly in thedevelopment of solar cells, nanostructured optical devices and high-resolutionbio-chemical sensors. Generally speaking, in this dissertation, This dissertation focuseson the optical characteristics of multi-configuration nanostructure arrays and the opticalcharacteristics of nanostructure arrays were simulated by using three-dimensionalfinite-difference time-domain (FDTD) method provided by FDTD Solutions(Lumerical). The main progresses of this work are listed as below:1. The antireflection characteristics of typical nanohole arrays and nanorod arraysbased on Si substrate were simulated by using FDTD method. Firstly, the antireflectioncharacteristics of nanorod arrays and nanohole arrays of three different kinds of shapes,including Cosine, parabola and cone shapes, based on Si substrate were studiedrespectively. It was concluded that for the nanorod arrays, cosine-shaped nanostructureis almost equal to the parabola-shaped one and better than the cone-shaped one in termsof antireflection and that for the nanohole arrays of different profiles, the antireflectionlevels are almost the same. Above all, a comparison between the antireflectioncharacteristics of nanorod arrays and the corresponding nanohole arrays was made andit was discovered that nanorod arrays are more suitable for broadband antireflectionthan nanohole arrays.2. The antireflection characteristics of inverted nanopyramid arrays wereinvestigated through the combination of fabrication and simulation. Firstly, a simple andeffective process based on NSL was presented for the fabrication of periodic invertednanopyramid structure. Secondly, the reflection spectra of the fabricated nanostructurewere obtained through a Hitachi, U-4100spectrophotometer. Moreover, the reflectionspectra of the nanostructure were obtained through FDTD simulation and the resultsagree well with experimental ones. At last, the influences of pyramid size and the latticeconstant of the nanopyramid array on the antireflection effect were further discussed.3. The transmission characteristics of typical nanohole arrays based on FDTDmethod were investigated. The influences of hole shape, perimeter distance of theaperture and the sharp tip effect on the EOT effect were analysised. It was concludedthat triangular holes have the maximum transmission efficiency among the threedifferent kinds of hole shapes of the same size and periodic ity and that the sharp tipeffect may have an influence on the EOT phenomenon in some cases.