Electrical and optical activation studies of Si-implanted GaN

Comprehensive and systematic electrical and optical activation studies of Si-implanted GaN were made as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1 X 10(13) cm(-2) to 5 X 10(15) cm(-2) at room temperature. The samples were proximity-cap annealed from 1050 degrees C to 1350 degrees C with a 500-angstrom-thick AlN cap in a nitrogen environment. The optimum anneal temperature for high dose implanted samples is approximately 1350 degrees C, exhibiting nearly 100% electrical activation efficiency. For low dose (<= 5 X 10(14) cm(-2)) samples, the electrical activation efficiencies continue to increase with an anneal temperature through 1350 degrees C. Consistent with the electrical results, the photoluminescence (PL) measurements show excellent implantation damage recovery after annealing the samples at 1350 degrees C for 20 sec, exhibiting a sharp neutral-donor-bound exciton peak along with a sharp donor-acceptor pair peak. The mobilities increase with anneal temperature, and the highest mobility obtained is 250 cm(2)/Vs. The results also indicate that the AlN cap protected the implanted GaN layer during high-temperature annealing without creating significant anneal-induced damage.