Effects Of Sputtering Parameters&Dopants On Surface Roughness&Hydrophobicity Of Graphite-like Amorphous Carbon Films Prepared By DC Magmetron Sputtering

To expand the application of GLC amorphous carbon films and clarify thehydrophilic/hydrophobic characteristics of its main influencing factors and mechanisms.Try tochange sputtering parameters which include bias voltage and C target current and dope otherelement such as Al,Si,Mo,W.The chemical composition,structure and morphology propertiesof the films were analyzed by XPS,SEM and AFM.On the basis of achieving effective controlof the sp2 bonding ratio,surface morphology/roughness and surface energy of thin films,the hydrophobicity of the films was examined by the contact angle measurement.The effects ofsputtering parameters and doping on the roughness and hydrophobicity of DC sputtering amorphous carbon films were clarified.Combined with the microscopic characteristics of the composition/structure and surface morphology/roughness and surface energy of the films,the mechanism of the change of its hydrophilicity and hydrophobicity was analyzed.At the same time,the degree of control of the hydrophobicity of GLC films prepared by DC magnetronsputtering and doping techniques was evaluated to obtain a preliminary optimization process basis.The investigative results indicated:The wettability of GLC films can be acutely changed through sp2 ratio,morphology and surface energy.The contact angles for water with the Cr-GLC films prepared by changing sputtering parameters were found to vary in the range 80.9°?110.2°.It means the wettability between hydrophilicity and hydrophobicity.The GLC films show hydrophobicity in special parameters.The Us has more significant effect on the hydrophobicity of Cr-GLC films than IC.At a fixed Ic of 2.5 A,the contact angle of the films increases from 80.9° to 107.6° as the US increases from-30 V to-90 V.The sp2 ratio increases from 0.47 to 0.59,and the roughness increases from 4 nm to 12 nm.It was concluded that sp2 ratio and roughness plays an important role on the hydrophobicity of the carbon films.At a fixed Us of-65 V,the sp2 bonding ratio and roughness of the films are reduced to some extent as the Ic increases from 1.0 to 2.5 A.The contact angles decreases from 110.2° to 102.3°,but all can show hydrophobic features.The effect of sputtering parameters on the surface energy is small,and there is no significant relationship between surface energy and hydrophobicityDifferent effect of doping element such as Al.Si?Mo?W on the hydrophobicity of Cr-GLC films.The wettability of Al/Cr-GLC films and Si/Cr-GLC films maintain the hydrophobicity.The wettability of Mo/Cr-GLC films and W/Cr-GLC films transform from hydrophobicity to hydrophilicity.A1 has the most significant effect on improving the hydrophobicity of films.With the content of A1 increases,the hydrophobicity increases.When the content of A1 is 2.4at%,Al/Cr-GLC films show the highest contact angle with water in this study,which reaches as high as 116.8°.Combining the changes in microscopic characteristics such as composition/structure and surface morphology/roughness and surface energy of the films,it is concluded that the increasement of sp2 ratio and Al-O bond have a significant effect on the hydrophobicity of Al/Cr-GLC films.With the content of Si increases,the water contact angle slightly changed from 96° to 102.8°.However,the addition of Mo and W into the films significantly improves the polar component of the surface energy and decreases the sp2 ratio and roughness.Three possible factors reduce the contact angle,leading to a significant decreased in the hydrophilicity of the films.