Group III nitride-based blue light-emitting diodes with a moth-eye structure at the bottom of a semi-insulating transport 6H-SiC substrate were fabricated. Self-assembled Au nanomasks and CF4 reactive ion etching were used for the fabrication of the moth-eye structure. We succeeded in forming cones with a mean period of approximately 160 mn and a mean height of approximately 400-600 mn. The period of 160 nm is shorter than the optical wavelength. The light extraction efficiency and the corresponding output power of the moth-eye-structured light-emitting diodes (LEDs) increased approximately three-fold those of LEDs with a conventional structure. (c) 2005 Elsevier B.V. All rights reserved.