Enhanced damage buildup in C-implanted GaN film studied by a monoenergetic positron beam

Li, X. F.*; Chen, Z. Q.*; Liu, C.*; Zhang, H.; Kawasuso, Atsuo

Journal of Applied Physics, 117(8), p.085706_1 - 085706_6, 2015/02

https://doi.org/10.1063/1.4913523

Vacancy-type defects in C-implanted GaN were probed using a slow positron beam. The increase of Doppler broadening S parameter indicates introduction of arge vacancy clusters. Post-implantation annealing at temperatures up to 800C makes these vacancy clusters to agglomerate into microvoids. The vacancy clusters or microvoids show high thermal stability, and they are only partially removed after annealing up to 1000C. Amorphous regions are observed by high resolution transmission electron microscopy measurement, which directly confirms that amorphization is induced by C-implantation. The disordered GaN lattice is possibly due to special feature of carbon impurities, which enhance the damage buildup during implantation.