InGaN/GaN light-emitting diodes with rapidly thermal-annealed Ni/ITO p-contacts

Ni (5 nm)/Au (5 nm) and Ni (5 nm)/indium-tin-oxide (ITO) (60 nm) films were deposited onto glass substrates, p-GaN epitaxial layers and nitride-based light-emitting diode (LED) structures. It was found that the normalized transmittance of subjected to rapid thermal annealing at 300°C Ni/ITO film (300°C-RTA) could reach 90.1% at 460 nm, which was much larger than that of the Ni/Au film. It was also found that the specific contact resistances were 5.0 × 10^-4 Ωcm², 1.3 × 10^-3 Ωcm² and 7.2 × 10^-4 Ωcm² for the Ni/Au, Ni/ITO and 300°C-RTA Ni/ITO contacts on p-GaN, respectively. Nitride-based LEDs with these p-contact layers were also fabricated. It was found that the LED with the 300°C-RTA Ni/ITO p-contact has a reasonably small operation voltage (i.e., 3.29 V at 20 mA). The 20 mA output intensity of the LED with the 300°C-RTA Ni/ITO p-contact is also 65% larger than that of the LED with the Ni/Au p-contact.