title: Manipulative depolarization and reflectance spectra of morphologically controlled nano-pillars and nano-rods.
abstract: Depolarization of sub-mum-high Si nano-pillar/nano-rod surface reflectance with morphologically controlled anti-reflection spectrum is demonstrated. Extremely small reflectance dip of 1.5% at 400-450 nm for Si nano-pillars is extraordinary when comparing with Si nano-rods, in which the reflectance vs. L/lambda for Si nano-pillars coincides well with the graded-index multilayer based modeling spectrum. Alternatively, Si nano-rods preserve its flattened reflectance spectrum up to 1700 nm, whereas the Si nano-pillar surface reflectance monotonically increases to approach that of bulk Si. The destructive interference is only induced on Si nano-pillar surface with larger aspect-ratio > or =15 and small sidewall slope <7 to suppress surface reflectance at blue-green wavelength region. Anomalous depolarization observed from disordered Si nano-pillar/nano-rod surface reflection indicates that TM-mode incidence interacts with more bound electrons than TE-mode to preserve its effective dielectric permittivity less deviated from the bulk Si. The degraded depolarization ratio observed under TE-mode incidence which correlates well with a simplified bounded-electron resonance model is elucidated.
authors.affiliation: 1Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University, No.1 Roosevelt Rd. Sec. 4, Taipei 106, Taiwan, R.O.C. grlin@ntu.edu.tw
authors.forename: Gong-Ru
authors.initials: GR
authors.lastname: Lin
authors.forename: Fan-Shuen
authors.initials: FS
authors.lastname: Meng
authors.forename: Yi-Hao
authors.initials: YH
authors.lastname: Pai
authors.forename: Yia-Chung
authors.initials: YC
authors.lastname: Chang
authors.forename: Shih-Hsin
authors.initials: SH
authors.lastname: Hsu
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons; D004867:Equipment Design; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D015233:Models, Statistical; D053758:Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D012825:Silicon / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D014466:Ultraviolet Rays
chemical_list: D012825:Silicon