Enhancement of electroluminescence in GaN-based light-emitting diodes (LEDs) was achieved using an efficient current blocking layer formed by postannealing, When a LED chip with Ni/Au pad on Ni/Au transparent p contact was annealed at 500 degrees C, the electroluminescence of the LED chip increased by 55%. The specific contact resistivity of metal contact below the p pad significantly increased due to indiffusion of Au and Ni atoms from the p pad to the contact interfacial region. As a result, an efficient current blocking layer could be formed below the p pad, enhancing the light output and decreasing the reverse leakage current of the LED chip, This result suggests that a further increase in the extraction efficiency of GaN-based LEDs can be easily obtained using the postannealing. (c) 2005 American Vacuum Society.