Novel Ni-Mg solid solution (5 nm)/Au (5 nm) schemes are investigated for the development of ohmic contacts to p-type GaN. It is shown that the samples annealed at 550 degreesC for I min in air ambient produce a specific contact resistivity of 3.0 x 10(-5) Omega cm(2). The light transmittance of the annealed samples is about 95% at a wavelength of 470 nm. GaN-based light-emitting diodes (LEDs) made with the annealed Ni-Mg solid solution/Au p-contact layers are fabricated. The typical I-V characteristics of the green LEDs with the annealed p-type contact layers reveal a forward-bias voltage of 3.32 V at an injection current of 20 mA, which is much better than that of the LEDs with Ni/Au contact layers. (C) 2004 Elsevier Ltd. All rights reserved.