MBE-Regrown Ohmics in InAlN HEMTs With a Regrowth Interface Resistance of 0.05 $\Omega\cdot\hbox{mm}$

Nonalloyed ohmic contacts regrown by molecular beam epitaxy were made on InAlN/AlN/GaN/SiC high-electron-mobility transistors (HEMTs). Transmission-line-method measurements were carried out from 4 K to 350 K. Although the total contact resistance is dominated by the metal/ n + -GaN resistance ( ~ 0.16 Ω·mm), the resistance induced by the interface between the regrown n + GaN and HEMT channel is found to be 0.05-0.075 Ω·mm over the entire temperature window, indicating a minimal barrier for electron flow at the as-regrown interface. The quantum contact resistance theory suggests that the interface resistance can be further reduced to be <; 0.02 Ω·mm in GaN HEMTs.