Electroluminescence Transition From Visible- to Ultraviolet-Dominant Mode in $\hbox {n-Mn}_{0.04}\hbox {Zn}_{0.96}\hbox {O/i-ZnGa}_{2}\hbox {O}_{4}\hbox {/} \hbox {n-GaN}$

We report an n-Mn_0.04Zn_0.96O(MZO) /i-ZnGa₂O₄/ n-GaN structure both as a light-emitting diode and as an ultraviolet (UV) photodetector at forward and reverse biases, respectively. The n-MZO films were prepared on n-GaN coated sapphire substrates, followed by postdeposition thermal annealing treatment at 700 ^°C, and an i-ZnGa₂O₄ interface layer was formed at the MZO/GaN interface after the annealing treatment. We found that the electroluminescence characteristics showed a transition from visible- to UV-dominant mode when the deposition temperature of the MZO film is from 100 ^°C to 300 ^°C. For the UV detection performance, the devices based on the low-temperature deposition (100 ^°C) of the MZO film showed the lowest dark current and the biggest ratio of photocurrent to dark current with a selectivity detectivity for 365 nm around light.