Optical study of Au/Ti/Ni/Mg-nanoparticles decorated zinc oxide heterostructures: size effect induced modulation of work function

Abstract

The development of the novel semiconductor heterogeneous functional materials is playing an ever more important role in materials and efficient devices with new properties and functions. In this work, heterostructures of Au/Ti/Ni decorated zinc oxide nanobelts were synthesized. The amount and diameter of metal nanoparticles were controlled by the sputtering time or the deposition time. The photoluminescence of metal/ZnO heterostructures has been investigated. Very strong enhancement of near-band-edge emission and simultaneous attenuation of visible emission were observed for ZnO nanobelts decorated with Au, Ti and Ni nanoparticles. But both the NBEUV and DL emission intensities of Ni/ZnO heterostructures decrease dramatically initially. A novel mechanism is proposed to explain observed kinds of experimental results based on characteristic of metal nanoparticles, LSPR, Purcell effects and work function change of nanosize induced. The Mg decorated zinc oxide nanobelts were synthesized for the first time. Then the entire mechanism was testified by the investigation on Mg/ZnO and Ni/ZnO heterostructures due to its much lower and higher work functions compared with that of ZnO nanobelts, respectively. The mechanism will facilitate the technical application of metal-nanoparticles decorated heterostructures, and be very useful for the creation of highly efficient optoelectronic devices.