Structural, Raman scattering and magnetic characteristics of Er+-implanted GaN thin films

• The ion implantation induced four new Raman phonon modes in the samples.
• All the samples were confirmed to be ferromagnetic at room temperature.
• The room-temperature ferromagnetism can be explained by the BMP theory.
• The coupling between Er3+ ions and electrons is stronger than that with holes.

Er+ ions were implanted into the n-type, unintentionally-doped (u-type) and p-type GaN epilayers, respectively. Subsequent rapid thermal annealing process was carried out at 800 °C in N2 ambience for 5 min. It is found that the micro-structure of GaN:Er films have a close relationship with the implantation and annealing process. Four new Raman peaks were introduced by Er+ ions implantation at 300, 362, 670 and 855 cm−1, respectively. All the samples exhibit room-temperature ferromagnetism, which can be well explained by the bound magnetic polaron theory. Our experiments also revealed that the magnetic properties of GaN:Er samples are closely related to their conduction type and initial carrier concentration, and the magnetic coupling between the magnetic moments of Er3+ ions and electrons is stronger than that with holes.