Two different types of ZnO-based light-emitting diode structures have been examined using a one-dimensional (ID) simulator that accounts for specific features of the hexagonal semiconductors-strong piezoeffects, existence of spontaneous electric polarization. low efficiency of acceptor activation, and high threading dislocation density (normally, similar to 10(7) - 10(9) cm(-2)) in the material. A hybrid ZnO/CdZnO/AlGaN/GaN structure grown on sapphire avoids problems in achieving robust p-type doping in ZnO. An all-ZnO approach employs a MgZnO/CdZnO/MgZnO double heterostructure grown on a ZnO substrate. Both Structures show a strong sensitivity of emission intensity to doping and layer thicknesses within our simulations. (c) 2005 American Vacuum Society.