ABSTRACT

The utilization of Zinc oxide (ZnO)-based heterostructures for optoelectronic applications like light-emitting diodes requires control not only of carrier density in the active ZnO channel but also in the surrounding barrier material for which (Mg,Zn)O is one promising candidate. Most experimental results published deal with properties of p-type (Mg,Zn)O thin films deposited on amorphous substrates, and much less data concerning the growth of p-type (Mg,Zn)O on bulk ZnO wafers, on sapphire, or uncommon substrate material for (Mg,Zn)O growth like GaAs are available. The effective mass of electrons increases with increasing Mg-content and explains differences observed for series with lower and higher Mg-content. In the case of excitation below the bandgap of the (Mg,Zn)O barriers, a single exponential decay is visible, while in the case of excitation above the bandgap of the barrier layers an additional process is visible in the transient. The excitons in the (Mg,Zn)O are trapped in potential fluctuations caused by alloy disorder and therefore exhibit a slow non-exponential decay.