The effect of SiC substrate microstructure and impurities on the phase formation in carbide-derived carbon
The effect of SiC substrate microstructure and impurities on the phase formation in carbide-derived carbon
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DOI：
10.1016/j.carbon.2010.11.035
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发表时间：
2011-04
期刊：
影响因子：
10.9
通讯作者：
V. Ischenko;Y. Jang;Martina Kormann;P. Greil;N. Popovska;C. Zollfrank;J. Woltersdorf
中科院分区：
文献类型：
--
作者：
V. Ischenko;Y. Jang;Martina Kormann;P. Greil;N. Popovska;C. Zollfrank;J. Woltersdorf
通过在高温下用Cl 2/H2气体混合物蚀刻不同的碳化硅（碳化物衍生的碳）来获得碳层。通过分析和高分辨率透射电子显微镜研究了所得层。已发现，高纯度单晶SiC晶片的蚀刻仅产生无定形碳。使用市售的烧结SiC和聚合物衍生的SiC，其中都含有硼和碳丰富的阶段，观察到石墨状和纳米金刚石夹杂物的发展。在商业多晶SiC衬底中，在大量的非氯化样品中发现了乱层石墨区域和孤立的金刚石颗粒的存在。这一事实表明，在商业SiC衬底的烧结过程中，金刚石相可能成核和生长。硼注入单晶SiC晶片的氯化表明，在SiC中单独存在的富硼掺杂剂不会引发金刚石相的成核。SiC衬底中似乎需要初始过剩的碳，正如硼掺杂聚碳硅烷衍生的SiC所示。量子化学计算辅助热力学考虑表明，在SiC氯化金刚石相的成核过程中，Cl 2/H2气体混合物中的氢的影响很小。
Carbon layers were obtained by etching of different silicon carbides with Cl2/H2gas mixtures at high temperatures (carbide-derived carbon). The resulting layers were studied by analytical and high resolution transmission electron microscopy. It was found, that etching of high purity single crystal SiC wafers exclusively yields amorphous carbon. The development of graphite-like and nanodiamond inclusions was observed using commercially available sintered SiC and polymer-derived SiC, which both contained boron- and carbon-rich phases. The presence of turbostratic graphite regions and isolated diamond particles in the bulk of non-chlorinated sample was revealed in the commercial polycrystalline SiC substrate. This fact points to the possible nucleation and growth of diamond phases during sintering of the commercial SiC substrate. Chlorination of boron-implanted single crystal SiC wafer showed that the presence of boron-rich dopants in the SiC alone does not trigger the nucleation of diamond phases. An initial surplus of carbon in the SiC substrates appeared to be required as could be shown for boron doped polycarbosilane derived SiC. Thermodynamic considerations assisted by quantum chemical calculations showed the low effect of hydrogen in the Cl2/H2gas mixtures during SiC chlorination for the nucleation of diamond phases.