Study of radiative defects using current-voltage characteristics in ZnO rods catalytically grown on 4H-p-SiC

High-quality ZnO rods were grown by the vapour-liquid-solid (VLS) technique on 4H-p-SiC substrate. The current transport mechanisms of the diodes at room temperature (RT) have been explained in termof the space-charge-limited currentmodel based on the energy band diagram of ZnO rods/4H-p-SiC heterostructure. The tunneling mechanism via deep-level states was found to be the main conduction process at low-applied voltage but at trap-filled limit voltage VTFL all traps are filled and the space-chargelimited current conduction dominated the current transport. From the RT current voltage measurements, the energy of the deep level trap and the trap concentration were obtained as ∼ 0.24 ± 0.02 eV and 4.4 × 1018cm-3, respectively. The deep level states observed correspond to zinc interstitial (Zni), responsible for the violet emission.