Very-Low Resistance Contact to 2D Electron Gas by Annealing Induced Penetration Without Spikes Using TaAl/Au on Non-Recessed i-AlGaN/GaN

A novel ohmic contact formation mechanism is revealed for the annealed Ta0.83 Al0.17/Au stacks on nonrecessed i-AlGaN/GaN. It is demonstrated that the contact metal alloy mainly composed by Au penetrates the AlGaN layer without apparent Ta-related solid phase reactions, establishing a spike-free contact to the 2D electron gas. A low contact resistivity of 0.14Ω ·mm (4.24E-7 Q·cm
²
) is then obtained after 900 °C/60s annealing.