Preparation And Field Emission Properties Of Ti/TiO₂-Diamond-like Carbon Films

Diamond-like Carbon(DLC)films as a functional material with the high hardness,low friction coefficient,low electron affinity,and good chemical and thermal stability,has a promising application prospect in cold cathode materials.However,the field emission performance of DLC films restricted by the limited electrical conductivity and the absence of special tip morphology on the surface prevents their application in cold cathode materials.To improve the field emission performance of DLC films,DLC films,Ti-doped DLC films and TiO₂-DLC composite films were prepared by magnetron sputtering coating technique and anodic oxidation method.Effect of the process parameters,Ti-doping and the TiO₂ as a loaded substrate on the structure and field emission properties of the DLC films were studied.The findings are as follows:(1)The study of regulating sputtering power and substrate bias voltage was carried out.It found that the turn-on field decreased with the increase of sputtering power,leading to the better field emission performance.When the sputtering power was of 200 W,the field emission performance was optimal with turn-on field of 4.77 V/?m.The turn-on field increased during sputtering power over 200 W,resulting in the dropped field emission performance.With the increases of the substrate negative bias voltage,the turn-on field decreased continuously,leading to the improved field emission performance.When the substrate negative bias was of 110 V,the field emission performance reached at the largest value of the turn-on field of 4.77 V/?m.Above all the optimal process parameters are sputtering power of 200 W and substrate negative bias of 110 V.(2)Ti-doped DLC films were prepared by using Ti-carbon composite targets.It found that the turn-on field decreased with the increase of Ti content,leading to the raised field emission performance.Moreover,when the Ti content is of0.16 wt.%,the ratio of sp³ and sp² bonds get suitable value,the turn-on field decreased to the lowest value of 2.40 V/?m,resulting in the peak value of field emission performance.However,with the continual increasing of Ti content,the turn-on field continually increased,resulting in the deteriorated field emission performance.(3)DLC films were deposited on TiO₂ nanotubes films.It found that DLC films appeared on TiO₂ nanotubes films with a state of amorphous carbon,and covered the surface tip of TiO₂ nanotubes.DLC films did not form a reliable combination with TiO₂ nanotubes.It found that the field emission current of composite films was worse than that of pure DLC films and TiO₂ nanotubes films.Above all the use of TiO₂ nanotubes film loading DLC didn't promote the field emission performance of DLC films,instead,decline the field emission performance of DLC films.