Increase in net donor concentration due to introduction of donor-like defects by ultra-low-dose Si-ion implantation and subsequent annealing in homoepitaxial n-type GaN

Si ions were implanted at a dose of 1 × 1010 cm−2 into a homoepitaxial n-type GaN layer with a net donor concentration (N D) of 3–8 × 1015 cm−3. The N D in the implanted region increased by 1–3 × 1015 cm−3 after annealing at a temperature greater than 900 °C compared with that for the as-grown homoepitaxial layer. The increase in N D was considerably larger than the peak concentration of implanted Si ions (3 × 1014 cm−3). No increase in N D was observed for an as-grown sample after annealing. These results clearly suggest that donor-like defects were introduced by implantation of Si ions and a subsequent annealing process.