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.
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A Study of Low-Annealing-Temperature Ohmic Contact on n-Type GaN LayersShyh-Chiang Shen, Georgia Institute of Technology, Atlanta, GAMinkyu Cho, Georgia Institute of Technology, Atlanta, GAMarzieh Bakhtiary Noodeh, Georgia Institute of Technology, Atlanta, GATheeradetch Detchprohm, Georgia TechRussell Dupuis, Georgia TechBarry Wu, Keysight Technologies, Inc.Don D’Avanzo, Keysight Technologies, Inc.Download Paper