  In this paper the design, fabrication and characterization of a bioinspired
overlayer deposited on a GaN LED is described. The purpose of this overlayer is
to improve light extraction into air from the diode's high refractive-index
active material. The layer design is inspired by the microstructure found in
the firefly Photuris sp. The actual dimensions and material composition have
been optimized to take into account the high refractive index of the GaN diode
stack. This two-dimensional pattern contrasts other designs by its unusual
profile, its larger dimensions and the fact that it can be tailored to an
existing diode design rather than requiring a complete redesign of the diode
geometry. The gain of light extraction reaches values up to 55% with respect to
the reference unprocessed LED.
