Figure 4

Normalized PL sprectra measured at room temperature. (a) Room temperature PL spectra of as-grown undoped and Ce-doped ZnO NRs. Two elementary PL spectra shown in dotted lines are obtained by deconvolution of the PL spectrum of doped ZnO NRs. The inset shows a schematic energy level diagram of Ce³⁺ electronic levels in ZnO bandgap. (b) Normalized PL spectra of ZnO NRs doped with different amounts of Ce molar contents.