中文摘要：

从能量和结构两个角度分析了BN四种相的转变过程，以及杂质和缺陷对立方氮化硼（c—BN）薄膜制备的影响．研究了从六角氮化硼（h-BN）到c—BN转变的一个可能的过程，即h—BN→菱形氮化硼（r．BN）→c—BN过程．对纯的h-BN到r-BN的转变需要克服一个很高的能量势垒，在实验室条件下很难能够提供能量来越过这个势垒．而从r-BN到c—BN的转变只需要克服一个很低的能量势垒．这个能量势垒要低于从h-BN到纤锌矿氮化硼（w—BN）转变所需要克服的能量势垒．c—BN薄膜的制备过程中，薄膜在高能粒子轰击下，会产生大量的缺陷，这些缺陷对立方相的形成起到了重要的作用，缺陷和杂质的存在大大降低了从h-BN到r-BN转变的能量势垒．根据这个理论模型，在两步法制备c—BN薄膜的基础上，调整实验参数，形成三步法制备高质量c—BN薄膜．主要研究了三步法中第一步的时间和衬底负偏压对c—BN薄膜制备的影响，找到合适的沉积时间和衬底负偏压分别为5min和-180V．采用三步法制备薄膜，可以重复得到高立方相体积分数（立方相体积分数超过80％）的BN薄膜，并且实验重复性达到70％以上．

英文摘要：

Phase transitions between the polytypes of boron nitride and the influence of defect and impurity on preparation of c-BN thin film are studied from energy and structure aspects. A pathway from h-BN to c-BN is analysed, namely： h-BN → r-BN → c-BN. The transformation from h-BN to c-BN is more difficult than that from r-BN to c-BN. The energy barrier is very high in direct transformation from h-BN to c-BN, but it is very low from r-BN to c-BN. In fact, defects and impurities in c-BN thin films may favorably drive the transformation from h-BN to c-BN. Defects and impurities can reduce the energy barrier for the transformation sufficiently enough for it to proceed under conditions obtainable in common laboratories. Based on the theoreticd model, we developed a new method to prepare c-BN thin film （three-step method）. The effect of time and substrate bias voltage on the first step of preparation of c-BN thin film is investigated. The study proves that 5 min and - 180V is very favorable. The c-BN thin film that content with cubic phase exceeding 80% can be repeatedly prepared using the three-step method. Results of experiments accord with the theoreticat model very well.