Yuta Ikeuchi

Low temperature ohmic contact for p-type GaN using Mg electrodes

Low Ohmic contact for p-type GaN (pGaN) has been of great importance for various applications including light emitting diodes and nitride based power devices. Although a low contact resistance (ρc) of the order of 10−6 Ωcm2 can be obtained with air-annealed Au/Ni electrodes, the hole transport relies on NiO islands inhomogeneously formed between the Au and the pGaN surface, giving concerns in long term reliability [1]. For Ti-based electrodes, on the other hand, an Ohmic contact can be achieved by forming an intermixed layer at the interface of the metal and pGaN surface, yet a relatively high temperature is required. Moreover, the ρc is reported to degrade along with time due to in-diffusion of hydrogen atoms stored in the metal layer during the high temperature annealing [2].