Structural and cathodoluminescence properties of ZnO nanorods after Ga-implantation and annealing

Single-crystalline ZnO nanorods were implanted with 30 keV Ga+ ions and fluences between 5×1012 and 1.5×1016 cm−2. Annealing treatments at temperatures up to 700 °C for 1 h were carried out to reduce implantation-induced structural defects. The structural and optical properties of the nanorods were studied by transmission electron microscopy (TEM) and cathodoluminescence (CL) spectroscopy. TEM shows that extended implantation defects vanish completely in nanorods implanted with doses up to 5×1013 cm−2 after annealing at 700 °C. Dislocation loops remain after implantation with higher fluences. The CL intensity of as-grown nanorods and implanted ZnO nanorods is low. Annealing at 700 °C leads to a significant increase in the CL intensity for as-grown nanorods and implanted with a dose of up to 5×1013 cm−2. The strong CL intensity in implanted and annealed nanorods correlates with the complete disappearance of extended structural defects.