Role of Capping Material and GaN Polarity on Mg Ion Implantation Activation

Ion implantation of magnesium for p-type GaN presents many opportunities; however, activation has proven difficult due to the decomposition of GaN at relevant annealing temperatures. Herein, testing the efficacy of multiple in situ and ex situ caps based on aluminum nitride and silicon nitride for GaN protection during annealing is presented. Photoluminescence shows better activation for in situ metal organic chemical vapor deposition (MOCVD)-grown aluminum nitride caps compared with ex situ sputtered aluminum nitride and the best performance by ex situ plasma-enhanced chemical vapor deposition (PECVD) silicon nitride. Furthermore, only samples annealed at the highest temperatures tested show preferential growth of UV luminescence to yellow-green luminescence reinforcing the need for better capping solutions and higher temperature annealing.