Electrical and optical activation studies of Si-implanted Al/sub x/Ga/sub 1-x/N by Hall-effect and photoluminescence measurements

Electrical and optical activation studies of Si-implanted Al/sub x/Ga/sub 1-x/N have been made as a function of ion dose, anneal temperature and anneal time. Silicon ions were implanted at 200 keV with doses ranging from 1/spl times/10/sup 13/ to 1/spl times/10/sup 15/ cm/sup -2/ at room temperature. The samples were proximity cap annealed from 1200 to 1350 /spl deg/C with a 500 /spl Aring/ thick AlN cap in a nitrogen environment. The activation efficiency and mobility increase with anneal temperature, indicating an improved implantation damage recovery. The electrical activation efficiencies of 65 and 87% were obtained for the Al/sub 0.25/Ga/sub 0.75/N samples implanted with doses of 1/spl times/10/sup 14/ and 1/spl times/10/sup 15/ cm/sup -2/, respectively, and annealed at 1350 /spl deg/C for 2 min. Both the electrical activation efficiency and Hall mobility of Si-implanted Al/sub 0.18/Ga/sub 0.82/N annealed at 1200 /spl deg/C for 5 to 25 min increase continuously with anneal time, but at a much slower rate as anneal time increases. The activation efficiency of 94% was obtained for a dose of 1/spl times/10/sup 15/ cm/sup -2/ after annealing at 1200 /spl deg/C for 25 min, which is the highest activation efficiency reported for a given dose, to the best of our knowledge. This result indicates that a longer anneal time at lower anneal temperatures could be a better alternative than a shorter anneal time at higher anneal temperatures.