Blue Light-Emitting Diodes Grown on ZnO Substrates

Blue light-emitting diodes (LEDs) grown on ZnO substrates were fabricated owing to the monolithic integration of an entire nitride-based LED structure including a GaN p--n junction and an (In,Ga)N/GaN multiple quantum well active region. The surface preparation of the ZnO substrate, as well as the GaN nucleation process, was developed to grow the structures and limit the inter diffusion of O from the substrate, which are the key points for the fabrication of a light-emitting device on ZnO. LEDs with a clear rectification behavior and electroluminescence over the blue range, from 415 to 450 nm, were demonstrated.