Enhanced field emission and hysteresis characteristics of aligned carbon nanotubes with Ti decoration

The field emission behavior of aligned carbon nanotubes (CNTs) is remarkably improved by decorating their surfaces with Ti nanoparticles through a sputtering process. The CNT/Ti(4 nm) sample shows a low turn-on field of 0.63 V/lm at 10 mu A/cm(2), low threshold field of 1.06 V/mu m at 1 mA/cm(2), and maximum field emission current density of 23 mA/cm(2) at 1.80 V/mu m. The enhanced field emission properties of the CNT/Ti samples are attributed to the added defect sites and Ti nanoparticles, which increase the field enhancement factor and density of emission sites. Stability measurements indicate that the Ti coating, which acts as a protective layer, also strengthens the field emission stability of the CNT arrays. Moreover, the extent of hysteresis in the current-voltage sweep highly depends on the voltage-sweep speed. (C) 2013 Elsevier B.V. All rights reserved.