Influence of pretreatment conditions of Ti film on field emission properties of carbon nanotubes films

Carbon nanotubes (CNTs) films have been synthesized from methane and hydrogen gas mixture by microwave plasma chemical vapor deposition (MPCVD) on Ti-coated Al₂O₃ substrates, which mechanically grinded by SiO₂ powder with Fe dopant. It is found that the grindness is a crucial effect to produce CNTs. By varying pretreatment conditions of the substrates such as no grinding, grinding and grinded acidly washing, the grinding and acidly washing can lower the turn-on field and improve the emission current density and emission light dots. The current density of the un-pretreated sample attains 0.015 mA/cm², but the grinding sample and grinded acidly washing sample attain 12.6 and 3.8 mA/cm², at the electric field of 3.7v/μm, respectively. The grinding sample shows the excellent field emission properties.