Molecular Dynamics And First Principles Studies Of Metal-Doped Diamond-Like Carbon Films

At present,metal doping has been proved to be able to reduce the residual stress in the film,but the physical mechanism of metal doping affecting the microstructure and physicochemical properties of the film is still lacking.In this paper,from the perspective of atomic weight,a systematic theoretical simulation of the dynamic growth of metal-doped DLC nanocomposite thin films was carried out,aiming to establish the interaction between the physical and chemical properties of the film and the internal microstructure,and to clarify the residual stress of metal-doped DLC Reduced universal physical mechanism.In this paper,molecular dynamics simulations and first-principles calculations are used to analyze the DLC films doped with the carbon-philic metal Cr and the weak-carbon metal Cu.The analysis of the film structure shows that the proportion of sp3-C hybridization in the film increases with increasing Cr and Cu content.There is no obvious change in bulk modulus in Cr-DLC;the bulk modulus in Cu-DLC increases with the increase of Cu concentration and then decreases.This is due to the formation of Cu metal clusters in the thin film structure network after the Cu concentration increases,which makes the Cu-DLC film The bulk modulus of the whole decreases.Compared with pure DLC,the residual stresses in Cr-DLC and Cu-DLC films show a trend of decreasing first and then increasing as the metal content increases.The analysis results show that the twisted bond angle and bond length are relaxed to the residual compressive stress of the film.The reduction has a significant effect.Under the condition of higher Me concentration,the proportion of twisted C-C bonds increases,and the formation of more twisted C-Me and Me-Me structures is the key factor leading to the increase of residual stress.Based on the above research,the structure and electronic properties of Cu / Cr co-doped DLC thin films are further analyzed.The results show that compared with the one-component metal doping,the Cu / Cr two-component co-doping has a more obvious effect on reducing the residual stress of the DLC film.Electronic structure analysis shows that there is a weak bond interaction between Cr and C atoms,and an anti-bond interaction between Cu and C atoms.The synergistic effect of the two increases the strain energy caused by the distortion of the atomic bond structure in the carbon network model.It plays a key role and can change the atomic bond structure without significantly increasing strain energy,which has an impact on the structural strength and stability of the film.