Low-resistance ohmic contacts on InAlN/GaN heterostructures with MOCVD-regrown n⁺-InGaN and mask-free regrowth process

This paper studied the low-resistance ohmic contacts on InAlN/GaN with metal--organic chemical vapor deposition (MOCVD) regrowth technique. The 150-nm regrown n⁺-InGaN exhibits a low sheet resistance of 31 Ω/□, resulting in an extremely low contact resistance of 0.102 Ω⋅mm between n⁺-InGaN and InAlN/GaN channels. Mask-free regrowth process was also used to significantly improve the sheet resistance of InAlN/GaN with MOCVD regrown ohmic contacts. Then, the diffusion mechanism between n⁺-InGaN and InAlN during regrowth process was investigated with electrical and structural characterizations, which could benefit the further process optimization.