Size-controllable synthesis of Bi/Bi2O3 heterojunction nanoparticles using pulsed Nd:YAG laser deposition and metal–semiconductor-heterojunction-assisted photoluminescence

Abstract

We synthesized Bi/Bi₂O₃ heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi₂O₃ heterojunction nanoparticles consisted of Bi nanoparticles and Bi₂O₃ surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi₂O₃ surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi₂O₃ surface layers, which are the metal–semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi₂O₃ nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi₂O₃ surface layers. The enhancement of PL emission at room temperature by metal–semiconductor-heterojunctions make the Bi/Bi₂O₃ heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes (LEDs) and laser diodes (LDs).