Electrical and optical activation studies of Si-implanted AlxGa1-xN by Hall-effect and photoluminescence measurements

Electrical and optical activation studies of Si-implanted Al_xGa_1-xN 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 1×10¹³ to 1×10¹⁵ cm^-2 at room temperature. The samples were proximity cap annealed from 1200 to 1350 °C with a 500 Å 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_0.25Ga_0.75N samples implanted with doses of 1×10¹⁴ and 1×10¹⁵ cm^-2, respectively, and annealed at 1350 °C for 2 min. Both the electrical activation efficiency and Hall mobility of Si-implanted Al_0.18Ga_0.82N annealed at 1200 °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 1×10¹⁵ cm^-2 after annealing at 1200 °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.