  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.
