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 1×10¹³ cm^?2 to 5×10¹⁵ cm^?2 at room temperature. The samples were proximity-cap annealed from 1050°C to 1350°C with a 500-Å-thick AlN cap in a nitrogen environment. The optimum anneal temperature for high dose implanted samples is approximately 1350°C, exhibiting nearly 100% electrical activation efficiency. For low dose (≤5×10¹⁴ cm^?2) samples, the electrical activation efficiencies continue to increase with an anneal temperature through 1350°C. Consistent with the electrical results, the photoluminescence (PL) measurements show excellent implantation damage recovery after annealing the samples at 1350°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 cm²/Vs. The results also indicate that the AlN cap protected the implanted GaN layer during high-temperature annealing without creating significant anneal-induced damage.