文摘
High-quality Mn:ZnO (MZO) film had been prepared on N-GaN coated sapphire substrates followed by postdeposition thermal annealing treatment at 700 掳C. For the annealed MZO/GaN heterojunction, a 15 nm cubic structural ZnGa2O4 layer was observed at the MZO/GaN interface through transmission electron microscope analysis. Through electroluminescence (EL) measurement, the formation of the nanointerface results in an EL transition from ultraviolet- to red-dominant mode for n-Mn:ZnO/N-GaN heterojunction light-emitting diodes (LEDs). The heterojunction LED showed a rectification ratio of 2.0 脳 105 at 卤2 V, a dark current of 3.5 nA at 鈭? V and a quite strong red EL with a low turn-on voltage of 3 V. On the basis of the energy band diagram, we think the EL transition from ultraviolet- to red-dominant mode is mainly due to the formation of a thin oxide blocking nanolayer at the MZO/GaN interface during the annealing process.
Keywords:
red electroluminescence; Mn:ZnO; light-emitting diodes; low turn-on voltage; nano- interface; ultraviolet- to red-dominant