This is a top-down SEM image of indium phosphide (InP) nanowires after growth. The nanowires are about 1.5 microns long and 0.18 microns in diameter, with a center to center distance of 0.47 microns (1 micron (μm) is equal to 1/1000 of a millimeter, that is, one millionth of a meter). This can be compared with the sunlight, which has most of its energy in a wavelength range from 0.5 to a few microns. The nanowires cover 12% of the surface as seen from top, that is, from the sun's point of view. On top of the nanowire is the gold particle which is used as a seed for the crystal growth. This image relates to a paper that appeared in Jan. 17, 2013, issue of Science Express, published by AAAS. The paper, by Jesper Wallentin at Lund University in Lund, Sweden, and colleagues was titled, "InP Nanowire Array Solar Cells Achieving 13.8% Efficiency by Exceeding the Ray Optics Limit."