磁场辅助激光生长类金刚石膜的微结构及光学性能

Micro-structural and optical properties of diamond-like carbon films grown by magnetic field-assisted laser deposition

在脉冲激光沉积技术中引入非均匀磁场,探索磁场约束激光等离子体条件下生长类金刚石膜的特性,为进一步提高类金刚石膜中sp~3键含量、增强微结构调控提供理论和实验基础.计算了磁场的磁感应强度及其磁力线分布,仿真了碳离子在磁场约束下的飞行轨迹,显示出磁场限制了碳离子的自由膨胀,使其螺旋前进并向永磁体中心区域聚集.膜层表面干涉和椭偏测量的拟合参数显示,磁场的磁感应强度越高,激光生长类金刚石膜的厚度及光学性能越不均匀.拉曼光谱及其拟合结果显示,磁场有利于提高碳网络结构的局部压力、提高膜层中的sp~3键含量.

Inhomogeneous magnetic field is introduced into pulsed laser deposition process,in order to find new properties of diamond-like carbon film grown under magnetic field,thereby offering the theoretical and experimental basis for further enhancing sp3-bond content in this film.Distribution of the magnetic strength and flux lines induced by a rectangular permanent magnet is calculated.And then,flying trace of the carbon ions in the magnetic field is also simulated by the iterative method,which indicates that the carbon ions cannot expand freely and they are confined and accumulate around the center region of the magnet source.Beside the surface interference,the measurement and the fitted results of ellipsometry parameters show that magnetic field exerts an important influence on layer-thickness distribution and optical constant of the pulsed laser deposition-grown diamond-like carbon film.Meanwhile,it is indicated that the inhomogeneity of the layer-thickness distribution and optical constant increase when the magnetic strength is higher.Micro-structure of diamond-like carbon film is affected seriously by magnetic field,which is indicated by Raman spectra.Magnetic field can enhance the local stress in the carbon matrix net,increasing the sp3-bond content.Theoretical research and experimental research both show that a suitable magnetic strength can excite micro-structure of diamond-like carbon film significantly,and the high-quality diamond-like carbon coating with practical application value will be obtained by technological adjustment.