Structure and ferromagnetism of Mn+ ion-implanted ZnO thin films on sapphire

Slow Positron Implantation Spectroscopy (SPIS), based on the generation, implantation and subsequent annihilation of mono-energetic positrons in a sample, has been used to stud), depth dependent vacancy-type damage in three ZnO films grown by pulsed laser deposition on c-plane sapphire. Doping was achieved by implantation of 250 keV Mn+ ions at 300 degrees C with three different fluences-10(16), 3 x 10(16), and 6 x 10(16) cm(-2). and Subsequent thermal annealing in air. Evolution of the open volume damage, its depth distribution, and the magnetic behavior was investigated by SPIS and Magnetic Force Microscopy. No indication of magnetic domain formation was found in any of the three films after implantation and the first annealing at 500 degrees C, whereas after the second annealing at 750 degrees C the two samples having the higher fluence showed stripe-like magnetic domains. (C) 2005 Elsevier Ltd. All rights reserved.