n-type ZnMnO spin injection layers were grown by pulsed laser deposition on top of n-ZnMgO/ZnO/p-AlGaN/p-GaN hybrid spin light-emitting diode (LED) structures synthesized by molecular-beam epitaxy. Both the ZnMnO/ZnMgO/ZnO/AlGaN/GaN structures and control ZnMnO samples show no or very low (up to 10% at the lowest temperatures) optical (spin) polarization at zero field or 5 T, respectively. This indicates difficulties in generating spin polarization by optical spin orientation or possible efficient spin losses. The results are similar to those found earlier for GaMnN/InGaN/AlGaN spin-LED structures and indicate that these wide-band-gap dilute magnetic semiconductors with weak spin-orbit interaction and hexagonal symmetry are not attractive for spin-LED applications. (c) 2006 American Vacuum Society.