Typical n-type ohmic contact formation for GaN material systems requires high-temperature thermal processes. The high-temperature process often leads to a rough surface after the annealing step. Low-annealing-ohmic contact is advantageous to prevent undesired surface roughening on the metal stack during this thermal process. We report an approach to achieve low contact resistance on n-type GaN layers using a nitrogen plasma and a conventional Ti/Al-based metal stacks. We observed an as-deposit ohmic contact behavior on the n-type contact with a specific contact resistance (rc,sp) in the mid-E-6 Ω∙cm2 range. The rc,sp was further reduced to 6.8E-7 Ω∙cm2 after an annealing step at 600 oC.