$p$-ZnO/$n$-GaN heterostructure ZnO light-emitting diodes

We report on the characteristics of a ZnO light-emitting diode (LED) comprised of a heterostructure of $p$-ZnO/$n$-GaN. The LED structure consisted of a phosphorus doped $p$-ZnO film with a hole concentration of $6.68×1017cm−3$ and a Si-doped $n$-GaN film with an electron concentration of $1.1×1018cm−3$⁠. The $I–V$ of the LED showed a threshold voltage of 5.4 V and an electroluminescence (EL) emission of 409 nm at room temperature. The EL emission peak at 409 nm was attributed to the band gap of $p$-ZnO which was reduced as the result of the band offset at the interface of $p$-ZnO and $n$-GaN.