掺杂元素对单晶式多晶体纳米金刚石复合薄膜形成的影响

Based on our previous study results，a new type of nano-structure, the single crystal like polycrystalline nano-diamond composite structure, has been proposed, which is an higher level ordered structure than that of single crystal. Comparing with the 0D bucky-balls, 1D nano-tubes, 2D graphene, it is a high ordered 3D nanostructures. With this ordered structure, nano-crystalline diamond films will have improved properties and a huge application value. . The focus of the proposed project is on the effects of doping elements on the formation mechanism of this kind of diamond composite film. The changes of the potential energy surface (PES) and the diffusion activation energy of carbon atoms, which are caused by different doping elements, will be deeply studied. The formation process of the ordered nano-structure will be divided into some sub-processes, namely, the ordered nucleation, the island uniform growth in all direction, and the interface formation. The self-organization and self-assembly of the deposited atoms in all the sub-processes will be investigated with the first principle calculation, the kinetic Monte Carlo simulation, and the relevant experiments, in order to identify the influence of the substrate surface morphology, the diffusions of deposited particles, the deposit temperature, and the deposit rate on the ordered nucleation, the island uniform growth, and the interface formation.. The research will present the theoretical basis for fabricating the high ordered nanostructure of diamond composite films.

单晶式多晶体纳米金刚石复合结构是依据我们以往研究提出的一种新型纳米结构。它是比单晶体更高层级的有序结构。对比0维-巴基球、1维-纳米管、2维-石墨烯，它是3维有序碳纳米结构。以此复合结构方式改进目前纳米金刚石薄膜，可使其具有更佳性能和巨大应用价值。. 本项目拟采用第一性原理计算、动力学蒙特卡罗仿真和相应科学实验探察掺杂元素对单晶式多晶体纳米金刚石复合薄膜形成的影响。研究不同掺杂元素造成碳粒子势能面、迁移激活能的变化。针对该有序纳米复合结构形成的几个基本过程（成核过程，岛生长过程，岛与岛相遇时界面形成过程），研究有序晶核形成、岛均匀长大、岛间界面形成与基底表面形貌、各种粒子迁移聚散、沉积温度、沉积率的关系，以揭示这类有序纳米复合结构形成过程中粒子自组织、自安装所遵循的规律。. 本项目的意义是为精确制备这类有序纳米复合薄膜提供理论依据。

本项目在认识金刚石薄膜生长和掺杂元素的作用方面取得重要进展。 1）在富Ar气氛下，CVD金刚石薄膜中超细纳米金刚石结构的形成源于碳粒子在清洁金刚石表面迁移困难和稳定等离子火团必需的真空腔高气压。在富氢气氛下，沉积碳粒子的吸附迁移与金刚石表面上氢原子的萃取密切相关。2）在富氢气氛下，金刚石薄膜的微观结构和结晶质量取决于掺杂原子对金刚石表面上氢原子的萃取。实际上，这与掺杂原子的核外电子层数和最外层电子数有紧密关系。3）硅掺杂或者磷掺杂可以导致薄膜中金刚石晶粒纳米化，而硼掺杂或者氮掺杂可以改善金刚石结晶质量，即增加薄膜中sp3相比例。4）根据这些研究结果，在富氢气氛下，制备n型或者p型超细纳米金刚石半导体薄膜的新途径是Si-N共掺杂或者Si-B共掺杂。.本项目发表资助号标注的学术论文20篇（SCI收录12篇）。获得国家发明专利一项；获内蒙古自治区自然科学三等奖一项。培养硕士生19人（毕业17人）。