title: Multicolored vertical silicon nanowires.
abstract: We demonstrate that vertical silicon nanowires take on a surprising variety of colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, or even to the naked eye. The reflection spectra of the nanowires each show a dip whose position depends on the nanowire radii. We compare the experimental data to the results of finite difference time domain simulations to elucidate the physical mechanisms behind the phenomena we observe. The nanowires are fabricated as arrays, but the vivid colors arise not from scattering or diffractive effects of the array, but from the guided mode properties of the individual nanowires. Each nanowire can thus define its own color, allowing for complex spatial patterning. We anticipate that the color filter effect we demonstrate could be employed in nanoscale image sensor devices.
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
authors.forename: Kwanyong
authors.initials: K
authors.lastname: Seo
authors.forename: Munib
authors.initials: M
authors.lastname: Wober
authors.forename: Paul
authors.initials: P
authors.lastname: Steinvurzel
authors.forename: Ethan
authors.initials: E
authors.lastname: Schonbrun
authors.forename: Yaping
authors.initials: Y
authors.lastname: Dan
authors.forename: Tal
authors.initials: T
authors.lastname: Ellenbogen
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Crozier
mesh_terms: D003116:Color; D003198:Computer Simulation; D008422:Materials Testing; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon