Defect clustering in irradiation of GaN by single and molecular ions

Abstract

Atomistic simulations were used to study irradiation effects on photoluminescence (PL) decay time of GaN. Irradiations were done by single (F, P) and molecular ions (PF4). Equal energy per mass (0.6 keV/amu) was used for all projectiles. Irradiation by the molecular ion shows faster PL decay time in comparison with the single ion. The simulation results show that single ions produce isolated point defects, whereas molecular ions produce big clusters of points defects. The total amount of defects produced by a PF4 projectile and five individual cascades started by one P and four F single ions (P + 4 × F) were very close and their defect depth profile follows the same pattern. These findings suggest that defect clusters are one of the important reasons for fast PL decay.