Structural, morphological and magnetic characteristics of Tb-implanted GaN and AlGaN films

Diluted-magnetic GaN:Tb and AlGaN:Tb films have been fabricated by implanting Tb+ ions into c-plane (0 0 0 1) GaN and AlGaN films and a subsequent annealing process. The structural, morphological and magnetic characteristics of the samples have been investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and superconducting quantum interference device (SQUID), respectively. The XRD and AFM analyses show that the annealing process can effectively recover the crystalline degradation caused by implantation. According to the SQUID analysis, both the GaN:Tb and the AlGaN:Tb films exhibit clear room-temperature ferromagnetism. It is very interesting to find the saturation magnetization value of the AlGaN:Tb sample is almost two times that of GaN:Tb sample. The possible origin of the ferromagnetism of the samples was discussed briefly.