ABSTRACT
ZnO-based p-n homojunction light emitting diodes (LEDs) have gained great progress in recent years [1-5]. However, their commercial applications face a big challenge due to the lack of a growth technique for realizing reproducible, stable, and high-quality p-type ZnO [6]. Although N is known to be the most likely genuine p-type dopant based on electronic structure and atomic size considerations, recent reports demonstrate that N cannot lead to p-type conductivity in ZnO [7,8]. An alternative approach is to fabricate heterostructured ZnO-based devices using other p-type materials to substitute the p-ZnO.
