Optical and magneto-optical properties of ZnCoO films grown at low temperature by Atomic Layer Deposition
are discussed. Strong wide band absorption, with onset at about 2.4 eV, is observed in ZnCoO in
addition to Co-related intra-shell transitions. This absorption band is related to Co 2+ to 3+ photo-ionization
transition. A strong photoluminescence (PL) quenching is observed, which we relate to Co recharging
in ZnO lattice. Mechanisms of PL quenching are discussed.