Effects of rapid thermal annealing on the electrical properties of cobalt contact to p-GaN

The effects of rapid thermal annealing (RTA) on Co/p-GaN contacts in an O-2 /N-2 atmosphere without intermediate metal were investigated. It was observ ed that the contact resistance (rho (c)) decreased with increasing RTA temp erature and that the resistance was reduced by a factor of about 30 after R TA at 600 degreesC in the O-2/N-2 atmosphere. The specific minimum contact resistance was in the 10(-2) Omega .cm(2) range. Comparison of the R-0 and rho (c) values revealed that the rapid thermal annealing in the O-2/N-2 was more effective for reducing the contact resistance than conventional furna ce annealing, The reason for the reduction of resistance was expected to be the increase of hole concentration due to the highly reactivated removal o f hydrogen atoms in the p-GaN by RTA in the O-2/N-2 atmosphere.