A Transmission Electron Microscopy study of Microstructure Evolutioin with Increasing Anneal Temperature in Ti/Al Ohmic Contacts to n-GaN

摘要

A(200 nm)/Ti(20 nm)-GaN contacts have beenstudied using transmission electron microscoipy (TEM) and the resulting microstructures correlated with the observed variation in specific contact resistance (#rho#_c). A minimum #rho#_c value of 7X10~(-7) #OMEGA#cm~2 was obtained after annealing at 550 deg C for 1 min in argon. Bulk metal and interfacial phases have been characterized, and explanations for the observed electrical behavior are proposed. A transition from TiN to AlN at the interface occurs between 650 deg C and 700 deg C.