Optical and magnetic properties of ZnO bulk crystals implanted with Cr and Fe

Optical absorption and microcathodoluminescence (MCL) bands were studied in heavily Cr and Fe implanted ZnO bulk crystals annealed at 700degreesC. The samples showed at room temperature hysteresis. The implanted regions remained n-type and optical absorption bands near 1.8 eV and the MCL bands near 2.8 eV were found to be associated with the transition metal (TM) ions. These bands are tentatively attributed to internal transitions between the levels of the substitutional TM ions. In addition to those bands we also observed strong absorption bands at 0.5 and 2.4 eV and MCL bands near 1.9 and 2.3 eV. All these bands are related to radiation damage defects. (C) 2004 Elsevier Ltd. All rights reserved.