Figure 4From: The origin of the red emission in n-ZnO nanotubes/p-GaN white light emitting diodes Schematic band diagram of the DLE emissions in ZnO based on the full potential linear muffin-tin orbital method and the reported data as described in references [9–20, 22]. Also oxygen vacancies situated 1.65 eV below the conduction band are denoted to be contributing to the red emission.Back to article page