Effect of MgO interface layer on photoelectric properties of n-ZnO nanorods/p-GaN heterojunction LED

Limited by the technology conditions, carrier concentration and Hall mobility of p-GaN are lower than those of n-ZnO. When the n-ZnO nanorods/p-GaN heterojunction device works under forward bias, the electroluminescence (EL) mainly origins from p-GaN side. In order to realize electroluminescence of n-ZnO, in this paper, heterojunction LEDs based on arrays of ZnO nanorods were fabricated on p-GaN films by hydrothermal method, and the effects of MgO interface layer on the photoelectric properties of the device are studied. The results show that all the devices demonstrate nonlinear rectifying behaviour. At room temperature, the EL spectra of the n-ZnO nanorods/p-GaN heterojunction diodes display one emission peak centered at about 430 nm under forward bias. However, the EL spectra of n-ZnO nanorods/MgO/p-GaN heterostructure LED exhibit a broad emission band from near ultraviolet to blue-green region. Combining the photoluminescence (PL) spectrum and Anderson energy band diagram, the mechanisms of radiative recombination in n-ZnO nanorods/p-GaN heterojunction LEDs are discussed in detail.