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.

Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

“…[5][6][7][8] This study focuses on the light trapping properties of semiconductor nanowire arrays, which arise from their subwavelength features. Semiconductor nanowires and nanowire arrays can exhibit remarkable optical phenomena, such as reduced reflectance, [9][10][11] enhanced absorption, [12][13][14][15] and spectral selectivity, [16][17][18] which arise due to efficient coupling into discrete photonic modes. For individual nanowires, the photonic modes have been identified as leaky waveguide modes, 6,16 which are resonantly excited via illumination perpendicular to their axis.…”

Mapping the directional emission of quasi-two-dimensional photonic crystals of semiconductor nanowires using Fourier microscopy

“…Nanowires grown by the vapor-solid-liquid (VLS) method have become a major field of research due to their unique optical properties. [11][12][13][14][15] The bottom-up approaches that are used to grow nanowires allow the combination of different semiconductors in single nanostructures despite the mismatches of the crystal lattice constant. This property has opened new opportunities to design a large variety of heterostructures.…”

Tuning Light Absorption in Core/Shell Silicon Nanowire Photovoltaic Devices through Morphological Design

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] For example, the optical properties of arrays of nano-and microscale wires have been exploited for enhanced light absorption in photovoltaic devices, [16][17][18][19] however, the ability to substantially manipulate absorption in individual nanoscale structures has not been well established. In order to quantify optical resonances supported in individual NWs, scattering [20][21][22] and absorption cross-sections 5,6,11,[23][24][25][26] have been measured or calculated.…”