화학공학소재연구정보센터
Applied Surface Science, Vol.345, 256-263, 2015
V2O5 nanoparticles grown on ZnO nanowires for enhanced field emission properties
To improve field emission (FE) properties of V2O5, ZnO nanowires were used as templates and V2O5 nanoparticles were successfully grown and coated on them via a chemical vapor deposition (CVD) route followed by a rapid anneal treatment. The particle size and shape were determined by the temperature sensitive crystallization of V2O5. Three different samples having different surface morphologies were obtained at 370, 450 and 510 degrees C, respectively, in which V2O5 nanoparticles were grown on the surface forming sharp tips. SEM results revealed that the sample of 450 degrees C had the sharpest tips, and its chemical states and components were examined by XRD analysis, confirming the coating of V2O5 on ZnO. FE measurements for the three samples showed enhanced FE properties compared with pure V2O5 and bare ZnO. Moreover, FE properties for the sample of 450 degrees C are the best in the three samples, showing a low turn-on field reduced markedly from 4.38 V/mu m (V2O5) to 2.25 V/mu m and a high current density (at 5 V/mu m) increased markedly from 0.21 mA/cm(2) (V2O5) to 4.98 mA/cm(2). The corresponding field enhancement factor (beta) also increased greatly to 3066, much higher than the value of pure V2O5 nanoparticles (beta(V2O5) approximate to 920) and higher than the value of bare ZnO (beta(Zno) approximate to 1590). The equipotential model analyses revealed that the enhanced FE properties were attributed to sharp tips formed by V2O5 nanoparticles, where the introduced V2O5 tips act as independent emitters on the surface and high local electric field around these tips increased the tunneling probability. (C) 2015 Elsevier B.V. All rights reserved.