n++GaN Regrowth Technique Using Pico-Second Laser Ablation to Form Non-Alloy Ohmic Contacts

Non-alloy ohmic contacts were implemented based on the heavily germanium-doped GaN regrown layer by using the pico-second laser ablation technique for the first time. Owing to the enhanced surface diffusion of the ablated high-energy atoms, smoothly refilled epitaxial layers were achieved in the AlGaN/GaN recess regions. Selective growth was successfully carried out by using hydrogen silsesquioxane (HSQ) film. Contact resistance of ~0.17 Q·mm with a specific contact resistance in the order of ~10
^-7
Ω·cm
²
was obtained by using non-alloy Hf/Al/Ti metal stacks.