InGaN/GaN Light-Emitting Diodes with Rapidly Thermal-Annealed Ni/ITO p-Contacts

Abstract

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.