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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.
The effects of impurities and defects on the preparation of cubic boron nitride (c-BN) thin films were analyzed from energy and structure perspectives. The effects of the transformation from hexagonal boron nitride (h-BN) to c -BN transition, that is, h-BN → rhombohedral boron nitride (r-BN) → c-BN process.The transition from pure h-BN to r-BN needs to overcome a very high energy barrier , It is very difficult to provide energy to overcome this barrier under laboratory conditions, whereas the transition from r-BN to c-BN only needs to overcome a very low energy barrier which is lower than that from h-BN To the w-BN (w-BN) transformation needed to overcome the energy barrier.C-BN film preparation process, the film in high-energy particle bombardment, there will be a large number of defects, these defects on the cubic phase formation Played an important role, the existence of defects and impurities greatly reduces the energy barrier of the transition from h-BN to r-BN.Based on this theoretical model, based on the two-step preparation of c-BN film, the experimental parameters are adjusted, The formation of three-step high-quality c-BN film prepared mainly studied the first step in three-step time and substrate negative bias on the c-BN film preparation to find the right The deposition time and the substrate negative bias were 5min and -180V, respectively.The BN films with high cubical phase volume fraction (cubic phase volume fraction more than 80%) were obtained repeatedly by the three-step method and the repeatability reached 70 %the above.