The Effects Of Magnetic Field On The Properties Of Carbon Nanomaterials(DLC) Films Prepared By Helicon Plasma

In this thesis,Diamond Like Carbon(DLC)films have been rapidly deposited on the silicon substrates by using a device called High Magnetic Field Helicon Experiment(HMHX).The effects of magnetic field intensity and substrate bias on the structure,surface morphology,chemical and mechanical properties of carbon nano-materials(DLC)were studied.At present,there are few studies on the preparation of carbon nano-materials by helicon wave plasma.DLC films prepared under different magnetic fields and biases show great difference in structure and thus the change of performance,so the research content of this subject has strong innovation and frontier.The Langmuir probe was used for the diagnosis and analysis of the plasma.The results showed that the plasma density first increased and then decreased with the increase of magnetic field intensity,and reached a peak at 2100Gs(about 2.2 X 1019m-3).The growth rate of thin films was consistent with that of plasma density.The increase of the magnetic field intensity leads to the decrease of the electron larmor radius,the decrease of the mean free path,the increase of the collision frequency,and the promotion of the effective transfer of energy between the electrons.When the magnetic field intensity increases to a certain extent,the plasma density may decrease due to the decrease of RF power coupling efficiency.The effect of active groups on the growth of thin films was studied by using the optical emission spectroscopy(OES).The increase of CH free group can promote the growth of DLC film,while the increase of C2 free radical is related to the increase of the proportion of non-diamond phase in DLC film.The structure and elemental composition of the films were measured and analyzed by Raman and XPS.The results showed that most of the C elements in the films exist as sp2 and sp3 phase.With the increase of magnetic field intensity,the content of C in the form of sp3 in the film also increases gradually,leading to the increase of the disorder degree of c-c bond angle.As the negative bias increases,the content of C in the form of sp3 in the film gradually decreasesThe roughness of DLC film was measured by atomic force microscope(AFM),the friction performance of film was studied,and the friction coefficient was calculated With the increase of magnetic field intensity,the roughness and friction coefficient of DLC film showed a trend of first increasing and then decreasing.The roughness and friction coefficient of DLC film decreased initially,followed by an increase with the increase of negative bias.By measuring the water contact angle,it is found that the water contact angle decreases first and then increases with the increase of the magnetic field intensity.With the increase of negative bias,the water contact angle first increases and then decreases.