Fabrication of p-type ZnO nanorods/n-GaN film heterojunction ultraviolet light-emitting diodes by aqueous solution method

Zinc oxide (ZnO) is a wide-bandgap material with excellent optical properties for optoelectronics applications. ZnO nanostructures are attractive for research because it is easy to fabricate in single-crystalline form and it has interesting physical properties at the nanoscale. In this paper, we report our successful growth of a p-type ZnO nanorods/n-GaN film heterojunction ultraviolet light-emitting diode (LED). The heterojunction LED shows its advantages over a p-ZnO film/n-GaN film heterojunction. The LED demonstrates a rectifying I-V characteristics with a turn-on voltage of 2.7V. The ideality factor is 6.5. The existences of interface charges in the interface are the reason for this low turn-on voltage and high ideality factor in the heterojunction. Electroluminescence (EL) spectra of the LED consist of an ultraviolet peak at 378nm and a broad yellow emission centered at 560nm. Fitting and comparing EL of the LED with PL of p-ZnO and n-GaN show that p-ZnO contributes more to the EL than n-GaN.