Synthesis, Characterization And Photoluminescence Studies Of In₂O₃ Nanomaterials

Indium oxide is a direct wide band gap semiconductor material. Indium oxide nanomaterials, such as nanowires, nanobelts and nanoparticles, have become the focus of intensive research due to their novel property and unique applications in nanoscale device. In this paper, a large number of indium oxide nanowires and nanoparticles without any impurity have been synthesized with a simple thermal evaporation method, assisted by active C powder. The morphology was characterized by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The composition was characterized by Energy Dispersive Spectroscope (EDS). The crystal structure was characterized by select area electron diffraction (SAED) and High-Resolution Transmission Electron Microscope (HRTEM). The relationship of morphology and growth temperature has been investigated. And the products were characterized in detail while the growth mechanism and the photoluminescence were investigated.The temperature and argon flow rate were used as the main parameters to produce nano-In₂O₃ in our experimental. In₂O₃ with different morphology were synthesized at different temperature and argon flow. The results show that the morphology of In₂O₃ changes from nanoparticles, nanorods to nanowires gradually as the temperature and argon flow rate increased. The growth mechanism of the nano-In₂O₃ was explained by the vapor-solid (VS). The different temperatures lead to the different growth rate along (100) and along (111) , resulting the different morphology of synthesized indium oxide nanoparticles. As the argon flow rate increases the supersaturation of In2O molecules decreases. The decrease of supersaturation of vapor molecules leads to the rapid decrease of vertical-growth speed of the nanomaterial, resulting the growth of nanowires.The analysis of the HRTEM and SAED indicates that the structure of the products is body-centered cubic structure and the crystal plane space is 0.253 nm corresponding to the (400). This is consistent with the XRD pattern, which show a preferred growth direction along <100>. The blue-green emission and near-band emission of In₂O₃ nanowires were found by the photoluminescence (PL) spectra at room temperature. It is suggested that the oxygen vacancy is responsible for strong blue emission. The supposition is confirmed by the results that the blue light emission peaks disappear after the products are oxidized annealing in air at 850℃And the blue light emission peaks appear again after the oxidized products are deoxidized annealing in H2 at 750℃. Our experimental results provide the proofs that blue light emission of In₂O₃ nanowires originates from oxygen vacancy.In summary, the synthesis of nano-In₂O₃ is explored and the growth mechanism is discussed. The temperature and argon flow play an important role in the morphology of the synthesized nano-In₂O₃. The PL experimental results support the supposition that the blue-green emission originates from oxygen vacancy. The experimental results are helpful for understanding the mechanism of the blue-green emission of nano-In₂O₃.