Enhanced 1.54 μm Luminescence in Er-doped ZnO Nanoparticle Films via Indirect Excitation

Abstract

AbstractPhotoluminescence (PL) of Er-doped ZnO nanoparticle films was studied. The films were fabricated using e-beam evaporation. The films were subsequently annealed at 700 °C in air for an hour. The atomic force microscopy (AFM) image revealed nano-sized ZnO particles. PL was measured at two excitation wavelengths, 325 and 514.5 nm. The 325 nm is used for exciting the ZnO host semiconductor and 514.5 nm is used for directly exciting Er3+ ions in the ZnO films. Er3+ luminescence was observed from the annealed film using either indirect (325 nm) or direct (514.5 nm) excitations. It has been found that the indirect excitation is about 40 times more efficient than the direct excitation in producing 1.54 μm PL. With indirect excitation, the Er3+ luminescence observed is attributed to energy transfer from ZnO host to the Er3+ ions doped. Energy transfer from e-h pairs resulting from ZnO host excitation may provide efficient routes for exciting Er3+ ions inside nano-crystalline particles of the films.